Electronic Device And Electronic Circuit

Home made UV PCB exposure box

2011-12-05T17:10:00.001-08:00

Examples and guidelines on how to do UV PCB exposure box by your self

UV LED PCB Exposure System

Home made UV LED PCB exposure boxPCB exposure box made with large array of UV LEDsThis project shows the creation of a large array of UV LEDs. They are used to expose a presensititised blank circuit board. Another common method is to use UV tubes. Alfredo has translated it to English as well as he could
more

Ultraviolet light source UV-80 for PCB exposure
Home made UV light PCB exposure boxPCB exposure box made with Ultraviolet light for Double side PCB exposure

One of more advanced PCB manufacturing methods is exposing laminate copper boards covered by photo resistive layer through mask. Using UV light in manufacturing PCB has many benefits according to other methods: you can get thin tracks like 0.2mm. You could do this by using other home techniques like laser printers or hand artwork
more

Single LED UV PCB exposure box
Home made UV LED PCB exposure boxPCB exposure box made with Single LED UV LZ1-10UA05

Having seen several attempts to make a PCB exposure box with LEDs instead of tubes, i decided to make my own.I wanted a smal one because i make prototypes one of a kind pcbs, and they are always small.Other projects i saw are using a large number of low power uv leds wich are in the miliwatt range. 80 Leds seems to be the minimum number to achieve 1W of UV radiated power, wich is what is needed to expose the PCB in a decent time.
more

Building a UV exposure box
Home made UV LED PCB exposure boxPCB exposure box made with array of UV LEDs for Double side PCB exposure

There are two methods of using etchant resist when making circuit boards. We use the toner transfer method that requires ironing on laser toner to the copper, but you can also use chemical resist that reacts to ultraviolet light. [Bogdan] decided to start doing more of the latter so he built a UV exposure box to make the process easier.
more

PCB Photographic Artwork Transfer UV Cabinet

Until now, to transfer the artwork to a photosensitive board, i used a pair of UV lamps. Although they worked pretty well, i thought of upgrading my lab. Thus, i designed and made a prototype photographic artwork transfer box using UV LEDs:
more

LED and Black light UV Light

Solar Power Center and Solar Charger Circuit

2011-06-15T18:23:00.000-07:00

Solar Power Center and Solar Charger Circuit

TLC2272 - 10 Amp out Solar Power Center
The SPC3 is a solar power center, it can handle all of the power functions for a solar charged 12 Volt DC system. The SPC3 contains a 9 amp photovoltaic charge controller, a 10 amp low voltage load disconnect circuit and a built-in white LED array for area illumination. The low voltage disconnect circuit has a load on-off switch, and a battery low voltage indicator. By using the SPC3 as the center of a solar powered device, long battery life is assured. The SPC3 can be used as a self-contained solar lighting system, it is also useful for making solar powered audio and radio devices and much more.
Specifications
Charge Controller Theory
Low Voltage Disconnect Theory
Charge Controller Alignment
Low Voltage Disconnect Alignment
SPC3 Circuit Extensions
more

AA Battery Solar Charger

Each of the solar cells develops about 0.5 volts across itself when in full sunlight. The string of 8 solar cells puts out around 4V with no load. When the solar cells are connected to a battery, a current will flow and the battery will charge.
Two versions of the circuit are shown in the schematic, the 8 solar cell panel with a diode is the recommended circuit. The diode prevents the battery from discharging through the cells at night and the 8th cell boosts the voltage up enough to compensate for the voltage drop across the diode. For an 8 solar cell panel, connect jumper J2 and disconnect J1. For a 7 solar cell panel, connect jumper J1 and eliminate SC8 and D1. Typically, the jumpers are not necessary, they are shown in the schematic to illustrate two ways to to build the circuit.
For operation in cloudy weather, it may be useful to add one or two additional solar cells. It is a good idea to temporarily insert an amp (microamp) meter in series with the battery to measure the charging current in various light conditions.
Since solar cells are current-limited devices, it is possible to use the circuit as-is to charge a single battery cell. If one cell is all you ever need to charge, five solar cells and a series diode will be sufficient for the task.
more

Solar charger for lead-acid batteries.

This circuit is intended for charging sealed lead-acid batteries with a solar panel in small and portable applications. The customary diode that prevents the battery from discharging through the solar panel has been replaced by a FET-comparator combination. The charger will stop charging once a pre-set voltage (temperature compensated) has been reached, and recommence charging when the voltage has dropped off sufficiently. The load is disconnected when the battery voltage drops below 11V and reconnected when it gets back to 12.5V.
more

SOLAR CHARGER

he circuit is a single transistor oscillator called a feedback oscillator, or more accurately a BLOCKING OSCILLATOR. It has 45 turns on the primary and 15 turns on the feedback winding. There is no secondary as the primary produces a high voltage during part of the cycle and this voltage is delivered to the output via a high-speed diode to produce the output. The output voltage consists of high voltage spikes and should not be measured without a load connected to the output. In our case, the load is the battery being charged. The spikes feed into the battery and our prototype delivered 30mA as a starting current and as the battery voltage increased, the charging current dropped to 22mA.
more

Basic Levitation and Magnetic Levitation Circuit Project

2010-02-04T16:34:00.000-08:00

Understanding Basic Levitation
In basic levitation (Fig 1) an object appears to float due to the invisible forces of magnets. A magnet creates a field that forms two opposing poles: North and South (Fig 2). Opposite poles attract each other while similar poles repel. For magnetic levitation, there is a fixed magnet and a smaller free moving permanent magnet, which is the object that will levitate. This object has two forces exerted on it: downward force from gravity and upward force from the fixed magnet.
http://icb.olin.edu/spring_04/ttgb/student/Ukiyo/understanding.htm

Magnetic Levitation Schematic Circuit

more

Levitation Photodetector Circuit
This optodetector measures the position of the ball by the amount of light transmitted by the infrared LED. This is a linear signal across the small area of the detector -- it is not just "on" and "off".

Levitation Difference Amplifier Circuit
This circuit creates a control signal from the two optodetectors. It finds the difference between the two input voltages and amplifies it to get the ball's position. This stage is often called a comparator.

Levitation Output Amplifier Circuit
This circuit amplifies the control signal in preparation for the power output transistor. Why do we need this stage at all? Because we reduced the whole signal by one-ninth in the speed-plus-position circuit.

more

Perpetual top Levitation Toy
The point of the perpetual top levitation toy is simply that it continues spinning forever, and the challenge is to understand the driving mechanism. The top is made of plastic, and contains embedded in it a small permanent magnet, oriented perpendicular to the spin axis of the top. The base contains a transistor and a coil with two windings, the assembly being driven by a 9-volt power supply. A schematic of the electrical circuit is shown in the figure.
As one pole of the magnet (say the south pole) approaches the coil, a current in induced in winding A, in such a direction as to make the base of the transistor (an NPN) go positive. That makes the emitter-collector current flow through winding B, in the opposite direction to A. The current through B is larger than that of A (due to the amplification of the transistor), so by Lenz's law the magnet pole will be attracted to the coil.

more

Magnetic Levitation Circuit
This is a simple magnetic levitator circuit which suspends objects a set distance below an electromagnet. The physics behind it is to simply provide a magnetic force which equal and opposite to the gravitational force on the object. The two forces cancel and the object remains suspended. Practically this is done by a circuit which reduces electromagnet force when an object gets to close, and increases it when the object is out of range.

more

MAGNETIC LEVITATION Project & CRITICAL TEMPERATURE KIT
ELECTRONICS CIRCUIT SCHEMATIC DIAGRAMS
The following figure is a schematic diagram for the Electronics Board.

Operation of the Electronics Board circuitry may be of interest to some students who use the Levitation/Critical Temperature kit. Individual circuit functions may be understood and analyzed from the following explanations. Operational amplifiers (op amps) are characterized by two nearly ideal properties, which lead to a wide variety of applications. These properties are 1) high impedance between the non-inverting and inverting inputs and 2) high open loop gain. Usually, both of these may be assumed to be infinite. Infinite impedance means no current flows between inputs, and infinite gain means that negative feedback will drive input voltage difference to zero. A variety of circuits can be analyzed using these two properties and Ohm's law.
more

Wireless Dimmer Circuit Project

2009-12-30T20:23:00.000-08:00

AVR wireless dimmer Project
At first we have to modify the layout of the old Avr dimmer. I don't think the RS232 interface will be used much when we have the wireless option available, so all the parts for the RS232 will have to go, the other thing that we don't really need anymore is the crystal with the 2 capacitors, because the ATtiny2313 has a build in RC clock of 4 and 8 Mhz which is more than sufficient. One more thing that could go is the infrared receiver, but this doesn't take much room on the circuit board so I will leave it on for the moment. The last thing we need to change is the power supply. The iDwaRF module needs between 2.7 to 3.6 Volts. The ATTiny2313 will run on a voltage between 2.7 to 5.5 volts and the infrared receiver needs 2,7 to 5,5 Volts if we use the TSOP 31236. So if we decide on a power supply of 3.3 Volts all the components will be happy.

Changing the voltage from 5 to 3.3 Volts sounds easier then it turned out to be. Negative regulators of -3.3 Volt are rare and if that is not all the Wireless module seems to have a peak current of more than 60 mA. Our old design could only supply an average of 20 mA. Also I want the dimmer to be power efficient, since I might end up with 10 or more dimmers, regulating everything in the house. So I am thinking of a switching regulator. This way we have a very efficient power supply that can temperarely supply higher currents. More will follow. This will need some testing.

At first we have to modify the layout of the old Avr dimmer. I don't think the RS232 interface will be used much when we have the wireless option available, so all the parts for the RS232 will have to go, the other thing that we don't really need anymore is the crystal with the 2 capacitors, because the ATtiny2313 has a build in RC clock of 4 and 8 Mhz which is more than sufficient. One more thing that could go is the infrared receiver, but this doesn't take much room on the circuit board so I will leave it on for the moment. The last thing we need to change is the power supply. The iDwaRF module needs between 2.7 to 3.6 Volts. The ATTiny2313 will run on a voltage between 2.7 to 5.5 volts and the infrared receiver needs 2,7 to 5,5 Volts if we use the TSOP 31236. So if we decide on a power supply of 3.3 Volts all the components will be happy.

Changing the voltage from 5 to 3.3 Volts sounds easier then it turned out to be. Negative regulators of -3.3 Volt are rare and if that is not all the Wireless module seems to have a peak current of more than 60 mA. Our old design could only supply an average of 20 mA. Also I want the dimmer to be power efficient, since I might end up with 10 or more dimmers, regulating everything in the house. So I am thinking of a switching regulator. This way we have a very efficient power supply that can temperarely supply higher currents. More will follow. This will need some testing.

http://domotica.homeip.net/dimmer3.html

IR Light Dimmer v.1
This is a device for adjusting lights in your home with any type of remote controller (tv, dvd, video,…). Today we are using many devices in our homes to improve quality of our life and this is another example on how you can enhance a simple procedure like switching the lights ON/OFF. It may be difficult to many of us to stand up from our chair only to switch lights, so try imagining yourself doing this with your remote controller.

http://www.electronics-lab.com/projects/motor_light/044/index.html

Projects/IR light dimmer v1
This is a very simple IR light dimmer that you will wish to have sooner or later, especially those who are lazy enough to get up and turn off the lights. There are two versions of PCB for two sizes of capacitors, so PCBs are: 32.5 x 26.5mm and 28.5 x 27mm.

Features of current beta version of firmware:
- Soft start (gradually turning on the light bulb)
- Soft down (gradually turning off the light bulb)
- Learning IR codes from RC5 and NEC remotes
- Dimming in 10 levels by using only IR remote
- Previous dimm-level remembering when operating with remote
- Sleep timer in duration of 1.6min for 60Hz version and 2min for 50Hz version
- ON/OFF control with wall pushbutton

http://www.elektronika.ba/617/ir-light-dimmer-v1

LM3445 TRIAC Dimmer Demo Video

High-Speed Leakage Circuit Breaker Circuit

2009-11-15T05:56:00.000-08:00

The value of R1, R2, C4, and C5 should be chosen in order to keep at least 12V in Vs.
Please connect C4 (>1μF) and C2 (<1μF).
ZCT and load resistance RL of ZCT are connected between input pin 1 and 2.
Protective resistance (RP=100Ω) must be insurted.
RL and amplifier’s output (in Pin 4) regulates sensitivity current
External capacitor C1 between pin 4 and GND is used for noise removal.
Please connect a varistor or a diode (2 pcs.) to ZCT in parallel, because of when large current is grounded in the
primary side (AC line) of ZCT, the following situation can be abandoned: The wave form in the secondary side of
ZCT is distorted and some signals do not appear in the output of amplifier.
Please connect capacitor (about 0.047μF) between pin 6 and pin 7.
Capacitor C6 between pin 1 and GND is about 0.047μF for removing noise.

M54123L
EARTH LEAKAGE CURRENT DETECTOR
DESCRIPTION
The UTC M54123L is a semiconductor integrated circuit with
amplifier for a high-speed earth leakage circuit breaker.
For the amplifying parts of earth leakage circuit breaker, the
UTC M54123L consists of differential amplifier, latch circuit and
voltage regulator.

In normal operating, the UTC M54123L should be connected
to the secondary side of the ZCT (zero current transformers). Here
the ZCT detects leakage current different amplifiers’ both input.
Then the signals which have been amplified are integrated by
an external capacitor. The integrated signal connects to the input
terminal of latch circuit whose output is suitable for the
characteristics of high- speed earth leakage circuit breaker.
Until the input voltage reaches the fixed level, latch circuit
doesn’t become high. Then drives a thyristor which is connected to
latch circuit’s output terminal.

FEATURES
* With good input sensitivity current temperature characteristics
* High input sensitivity :VT=6.1mV (Typ.)
* Only need low external component count
* High noise and surge-proof
* Low power dissipation :PD=5mW (Typ.)
* May be used both as 100V and 200V.
* Wide temperature range : from -20 °C to +80°C

Datasheet
http://www.unisonic.com.tw/datasheet/M54123L.pdf

CAN BUS Interface With Microcontroller by SPI Circuit

2009-11-10T18:32:00.000-08:00

SYSTEM IMPLEMENTATION

MCP2515
Description
Microchip Technology’s MCP2515 is a stand-alone
Controller Area Network (CAN) controller that implements
the CAN specification, version 2.0B. It is capable
of transmitting and receiving both standard and
extended data and remote frames. The MCP2515 has
two acceptance masks and six acceptance filters that
are used to filter out unwanted messages, thereby
reducing the host MCUs overhead. The MCP2515
interfaces with microcontrollers (MCUs) via an industry
standard Serial Peripheral Interface (SPI).

Features
• Implements CAN V2.0B at 1 Mb/s:
- 0 – 8 byte length in the data field
- Standard and extended data and remote
frames
• Receive buffers, masks and filters:
- Two receive buffers with prioritized message
storage
- Six 29-bit filters
- Two 29-bit masks
• Data byte filtering on the first two data bytes
(applies to standard data frames)
• Three transmit buffers with prioritizaton and abort
features
• High-speed SPI™ Interface (10 MHz):
- SPI modes 0,0 and 1,1
• One-shot mode ensures message transmission is
attempted only one time
• Clock out pin with programmable prescaler:
- Can be used as a clock source for other
device(s)
• Start-of-Frame (SOF) signal is available for
monitoring the SOF signal:
- Can be used for time-slot-based protocols
and/or bus diagnostics to detect early bus
degredation
• Interrupt output pin with selectable enables
• Buffer Full output pins configurable as:
- Interrupt output for each receive buffer
- General purpose output
• Request-to-Send (RTS) input pins individually
configurable as:
- Control pins to request transmission for each
transmit buffer
- General purpose inputs
• Low-power CMOS technology:
- Operates from 2.7V – 5.5V
- 5 mA active current (typical)
- 1 µA standby current (typical) (Sleep mode)
• Temperature ranges supported:
- Industrial (I): -40°C to +85°C
- Extended (E): -40°C to +125°C

http://ww1.microchip.com/downloads/en/DeviceDoc/21801d.pdf

ADC AND I/O CAN BUS Circuit

2009-11-02T18:29:00.000-08:00

MCP2502X/5X
Description
The MCP2502X/5X devices operate as I/O expanders
for a Controller Area Network (CAN) system,
supporting CAN V2.0B active, with bus rates up to
1 Mb/s. The MCP2502X/5X allows a simple CAN node
to be implemented without the need for a
microcontroller.

The MCP2502X/5X devices feature a number of
peripherals, including digital I/Os, four-channel 10-bit
A/D (MCP2505X) and PWM outputs with automatic
message transmission on change-of-input state. This
includes an analog input exceeding a preset threshold.

Features
• Implements CAN V2.0B
- Programmable bit rate up to 1 Mb/s
- One programmable mask
- Two programmable filters
- Three auto-transmit buffers
- Two message reception buffers
- Does not require synchronization or
configuration messages
• Hardware Features
- Non-volatile memory for user configuration
- User configuration automatically loaded on
power-up
- Eight general-purpose I/O lines individually
selectable as inputs or outputs
- Individually selectable transmit-on-pinchange
for each input
- Four 10-bit, analog input channels with
programmable conversion clock and VREF
sources (MCP2505X devices only)
- Message scheduling capability
- Two 10-bit PWM outputs with independently
programmable frequencies
- Device configuration can be modified via
CAN bus messages
- In-Circuit Serial Programming™ (ICSP™) of
default configuration memory
- Optional 1-wire CAN bus operation
• Low-power CMOS technology
- Operates from 2.7V to 5.5V
- 10 mA active current, typical
- 30 µA standby current (CAN Sleep mode)
• 14-pin PDIP (300 mil) and SOIC (150 mil)
packages
• Available temperature ranges:
- Industrial (I): -40°C to +85°C
- Extended (E): -40°C to +125°C

http://ww1.microchip.com/downloads/en/DeviceDoc/21664D.pdf

USB Keyboard by Microcontroller with Embedded Hub Circuit

2009-10-19T17:17:00.000-07:00

The Atmel sample version of the AT43USB326 contains firmware
that supports customization of the Vendor ID, Product ID,
String Descriptor and the keyboard matrix. This information
is stored in an external AT24C02A serial EEPROM.

The Atmel AT43USB326 is an 8-bit microcontroller based on the
AVR RISC architecture. By executing powerful instructions in
a single clock cycle, the AT43USB326 achieves throughputs
approaching 12 MIPS. The AVR core combines a rich instruction
set with 32 general-purpose working registers. All 32 registers
are directly connected to the ALU allowing two independent
registers to be accessed in one single instruction executed in
one clock cycle. The resulting architecture is more code efficient
while achieving throughputs up to ten times faster than
conventional CISC microcontrollers.

Features
• AVR® 8-bit RISC Microcontroller with 83 ns Instruction Cycle Time
• USB Hub with One Attached and Two External Ports
• USB Keyboard Function with Three Programmable Endpoints
• 16 KB Program Memory, 512 Bytes Data SRAM
• 32 x 8 General-purpose Working Registers
• 32 Programmable I/O Port Pins
• Support for 18 x 8 Keyboard Matrix
• Keyboard Scan Inputs with Pull-up Resistor
• Four LED Driver Outputs
• One 8-bit Timer/Counter with Separate Pre-scaler
• External and Internal Interrupt Sources
• Programmable Watchdog Timer
• 6 MHz Oscillator with On-chip PLL
• 5V Operation with On-chip 3.3V Power Supply
• 48-lead LQFP Package

http://www.atmel.com/dyn/resources/prod_documents/doc3313.pdf

PS/2 SCROLLING MOUSE CONTROL CIRCUIT

2009-10-07T18:00:00.000-07:00

DESCRIPTION
The UT84520 Scrolling Mouse Controller is specially
designed to control PS/2 mouse device．This single chip can
interface with three key-switches and 4X-Y photo-couples plus
Z-axis directly to 8042 controller．
There are four types of Z-axis inputs used to implement
scrolling mouse functionality．

FEATURES
*Using 50KΩ+5% resistor for RC oscillation．
*Compatible with legacy PS/2 mouse．
*Compatible with Microsoft PS/2 scrolling mouse．
*Built-in noise immunity circuit．
*The sampling rate of motion detector is up to 65KHz．
*Built-in three step dynamic input impedance．
*Three key-switches and four photo-couples inputs．
*Photo couple test mode included﹒
*Low power dissipation．
*Two types Z direction input:
1.Photo couples input
2.Mechanical input

Basic Electronic Lecture Vedio

2009-08-29T19:49:00.000-07:00

Active Diode Circuits Lecture Vedio

Oscillatiors Lecture Vedio

Logarthmic and Anti-Logarthmic Amplifer Lecture Vedio

Filters Lecture Vedio

Unit Junction Transistor Lecture Vedio

Inductive Touch Sensing Keyboard Circuit

2009-08-11T18:46:00.000-07:00

Figure shows an example for a 4-key Inductive Touch Sensing keyboard
with key controlled by the IO pins of the PIC® MCU.

The PIC® microcontroller is used to generate a squarewave signal and
to do all the necessary operations forproper detection of the key press event.

Then, RIN-CIN filter converts the square wave output ofthe PWM into
a quasi-triangular waveform.

To calculate the amplitude of the triangular signal, thestandard charging
time equation for an RC network willbe used

MCP2036
DescriptionThe MCP2036 Inductive Sensor Analog Front End(AFE)
combines all the necessary analog functions fora complete inductance
measurement system.The device includes :• High-frequency,
current-mode coil driver forexciting the sensor coil.• Synchronous detector
for converting AC sensevoltages into DC levels.• Output amplifier/filter to
improve resolution andlimit noise.• Virtual ground reference generator for
singlesupply operation.

Features
• Complete Inductance Measurement System:
- Low-Impedance Current Driver
- Sensor/Reference Coil Multiplexer
- High-Frequency Detector
• Operating Voltage: 2.7 to 5.5V
• Low-Power Standby Mode
• Gain and Frequency set by external passivecomponents

MCP2036 Datasheet pdf
http://ww1.microchip.com/downloads/en/DeviceDoc/22186A.pdf

Introduction to Inductive Touch Sensing Vedio

Introduction to mTouch Inductive Touch Sensing Part 1

Introduction to mTouch Inductive Touch Sensing Part 2

Operation Amplifier Circuit and Application Lecture Vedio

2009-08-02T18:00:00.000-07:00

Characteristics of Operation Amplifier Lecture Vedio

Characteristics of Operation Amplifier Lecture Vedio

Characteristics of Operation Amplifier Lecture Vedio

Inverter/Non-Inverter Circuits Lecture Vedio

Applications of Op Amps Lecture Vedio

Non-Linear Op Amp circuits Lecture Vedio

Applications of Op Amps Lecture Vedio

Typical Characteristic of Operation Amplifier and Types of Feed Back Lecture Vedio

2009-07-27T18:23:00.000-07:00

Typical Characteristic of Operation Amplifier Lecture Vedio

Four Types of Feed Back Lecture Vedio 1

Four Types of Feed Back Lecture Vedio 2

Mathematical Operations Lecture Vedio

Mathematical Operations 1 Lecture Vedio

Mathematical Operations 2 Lecture Vedio

Transistor Biasing, Frequency Analysis and Amplifer Lecture Vedio

2009-07-13T18:06:00.000-07:00

Transmission of Analog Signal – II Lecture Vedio

Transistor Biasing Lecture Vedio

Basic Characteristic of an Amplifer Lecture Vedio

Hybrid Equivalent Circuit, H-Parameters Lecture Vedio

Circuit Analysis using H-Parameters Lecture Vedio

Frequency Analysis Vedio

Frequency Response of Amplifiers Lecture Vedio

Frequency Analysis Lecture Vedio

Amplifiers Lecture Vedio

Power Amplifiers Lecture Vedio

Differential Amplifiers CKT Lecture Vedio

Basic Diodes Lecture Vedio

2009-07-05T02:53:00.000-07:00

Semi Conductor Diodes Lecture Vedio

Applications of Diodes Lecture Vedio

Wave Shaping using Diodes Lecture Vedio

Zener Diode Characteristics Lecture Vedio

Basic Electronics and Electronic Devices Lecture Vedio

2009-06-20T21:23:00.000-07:00

Introduction to Basic Electronics Lecture Vedio

Electronic Devices 1 Lecture Vedio

Electronics Devices Lecture Vedio

Some Useful Laws in Basic Electronics Lecture Vedio

Some Useful Theorems in Basic Electronics Lecture Vedio

BRUSHLESS DC MOTOR Driver Circuit

2009-06-13T01:42:00.001-07:00

Closed Loop Brushless DC Motor Control Circuit

Brushless DC Motor Controller
The MC33035 is a high performance second generation monolithic
brushless DC motor controller containing all of the active functions
required to implement a full featured open loop, three or four phase
motor control system. This device consists of a rotor position decoder
for proper commutation sequencing, temperature compensated
reference capable of supplying sensor power, frequency
programmable sawtooth oscillator, three open collector top drivers,
and three high current totem pole bottom drivers ideally suited for
driving power MOSFETs.

The MC33035, by itself, is only capable of open loop
motor speed control. For closed loop motor speed control,
the MC33035 requires an input voltage proportional to the
motor speed. Traditionally, this has been accomplished by
means of a tachometer to generate the motor speed feedback
voltage. Figure 39 shows an application whereby an
MC33039, powered from the 6.25 V reference (Pin 8) of the
MC33035, is used to generate the required feedback voltage
without the need of a costly tachometer. The same Hall
sensor signals used by the MC33035 for rotor position
decoding are utilized by the MC33039. Every positive or
negative going transition of the Hall sensor signals on any
of the sensor lines causes the MC33039 to produce an output
pulse of defined amplitude and time duration, as determined
by the external resistor R1 and capacitor C1. The output train

of pulses at Pin 5 of the MC33039 are integrated by the error
amplifier of the MC33035 configured as an integrator to
produce a DC voltage level which is proportional to the
motor speed. This speed proportional voltage establishes the
PWM reference level at Pin 13 of the MC33035 motor
controller and closes the feedback loop. The MC33035
outputs drive a TMOS power MOSFET 3−phase bridge.
High currents can be expected during conditions of start−up,
breaking, and change of direction of the motor.

The system shown in Figure 39 is designed for a motor
having 120/240 degrees Hall sensor electrical phasing. The
system can easily be modified to accommodate 60/300
degree Hall sensor electrical phasing by removing the
jumper (J2) at Pin 22 of the MC33035.

2.8A THREE-PHASE BRUSHLESS DC MOTOR Driver Circuit

DMOS DRIVER FOR THREE-PHASE BRUSHLESS DC MOTOR
The L6235 is a DMOS Fully Integrated Three-Phase
Motor Driver with Overcurrent Protection.
Realized in MultiPower-BCD technology, the device
combines isolated DMOS Power Transistors with
CMOS and bipolar circuits on the same chip.
The device includes all the circuitry needed to drive a
three-phase BLDC motor including: a three-phase
DMOS Bridge, a constant off time PWM Current Controller
and the decoding logic for single ended hall
sensors that generates the required sequence for the
power stage.

A typical application using L6235 is shown in Figure 21.
Typical component values for the application are shown
in Table 3. A high quality ceramic capacitor (C2) in the
range of 100nF to 200nF should be placed between the
power pins VSA and VSB and ground near the L6235 to
improve the high frequency filtering on the power supply
and reduce high frequency transients generated by the
switching. The capacitor (CEN) connected from the EN
input to ground sets the shut down time when an over
current is detected (see Overcurrent Protection). The two
current sensing inputs (SENSEA and SENSEB) should be
connected to the sensing resistor RSENSE with a trace
length as short as possible in the layout. The sense
resistor should be non-inductive resistor to minimize
the di/dt transients across the resistor. To increase noise
immunity, unused logic pins are best connected to 5V
(High Logic Level) or GND (Low Logic Level) (see pin
description). It is recommended to keep Power Ground
and Signal Ground separated on PCB.

175-V, 2-A, two-quadrant velocity controller Driver Circuit

The UCC3626 motor controller device combines
many of the functions required to design a
high-performance, two- or four-quadrant, threephase,
brushless dc motor controller into one
package. Rotor position inputs are decoded to
provide six outputs that control an external power
stage. A precision triangle oscillator and latched
comparator provide PWM motor control in either
voltage- or current-mode configurations. The
oscillator is easily synchronized to an external
master clock source via the SYNCH input.
Additionally, a QUAD select input configures the
chip to modulate either the low-side switches only,
or both upper and lower switches, allowing the
user to minimize switching losses in less
demanding two-quadrant applications.

Figure illustrates a simple 175-V, 2-A, two-quadrant
velocity controller using the UCC3626. The power stage
is designed to operate with a rectified off-line supply using
IR2210s to provide the interface between the low
voltage control signals and the power MOSFETs.

Microcontroller to USB Serial Interface Circuit

2009-04-15T17:50:00.000-07:00

Microcontroller to USB UART Interface Circuit

Figure 7.4 USB to MCU Serial Interface
An example of using the FT232R as a USB to Microcontroller
(MCU) UART interface is shown in Figure 7.4. In this application
the FT232R uses TXD and RXD for transmission and reception of
data, and RTS# / CTS# signals for hardware handshaking. Also
in this example CBUS0 has been configured as a 12MHz output to
clock the MCU. Optionally, RI# could be connected to another I/O
pin on the MCU and used to wake up the USB host controller from
suspend mode. If the MCU is handling power management functions,
then a CBUS pin can be configured as PWREN# and would also be
connected to an I/O pin of the MCU.

FT245BM datasheet pdf

Implementation USB to microcontroller (AVR)

Purpose of this article is to inform readers about implementation
USB interface into singlechip microcontroller, which this interface
directly not supports. Simply: implementation USB interface on
firmware level (similar as emulation of RS232 Serial interface in
microcontrollers, which not have RS232 Serial support). This project
includes development of firmware on microcontroller side, driver
development on computer side (for Windows operating system) ,
development of DLL library for functions calling from another
programs (programmers level) and development of demo program
(users level), which shows all functions of this device. Device is
named IgorPlug-USB (AVR) (as successor of my previous device
for computer remote control IgorPlug - serial port version).

Universal USB interface
more

WIDER POSITION SENSING CIRCUIT

2009-04-11T10:17:00.000-07:00

To go from 45° to 90° requires two HMC1501
sensors or a single HMC1512 dual sensor part. By
using two bridges with 45° displacement from each
other, the two linear slopes can be used additively.
Figure 8 shows a typical configuration.
From Figure 8, as the shaft rotates around, magnetic
flux from a magnet placed at the end of the shaft exits
the north pole and returns to the south pole. With a
HMC1512 placed on the shaft axis, just above the
magnet, the flux passing through the sensor bridges
will retain the orientation of the magnet. From this
rotation, the output of the two bridges will create sine
and cosine waveforms as shown in Figure 9.

Because the sine (sensor bridge A) and cosine
(sensor bridge B) will match after the offset error
voltages are subtracted, the ratio of bridge A to bridge
B creates a tangent 2O function and the amplitude A
values cancel. Thus the angle theta is described
as:

However because there are some trigonometric
nuances with the arctangent function when gets
close to _45° and beyond, these special cases apply:

Because most trigonometric functions are performed
as memory maps in microcontroller integrated circuits,
these kinds of special case conditions are easily dealt
with. The resultant angle theta is the relative
position of the magnetic field with respect to the
sensor. It should be noted that if rotation is permitted
beyond _90°, the theta calculation will replicate again
with postive and negative 90° readings jumping at the
end points. Further performance to 360° or _180° can
be mapped into a microcontroller by using this circuit
plus a Hall Effect sensor to determine which side of
the shaft is being positionally measured via magnetic
polarity detection. Figure 10 shows the basic circuit
interface for the HMC1512.

Source
http://www.ssec.honeywell.com/magnetic/datasheets/an211.pdf

HMC1501 / HMC1512
Linear / Angular / Rotary
Displacement Sensors
High resolution, low power MR sensor capable of measuring the angle
direction of a magnetic field from a magnet with <0.07>

HMC1501 Datasheet pdf

Snubber Circuit Design

2009-04-09T11:21:00.000-07:00

Mosfet RCD Snubber Circuit Design

Design the MOSFET RCD snubber circuit

Push-Pull Snubber Circuit

Mosfet Snubber Circuit in Flyback Converter Circuit

Switch Protection Design - Fast-Recovery Diodes

Magnetic Rotary Encoder to Microcontroller Circuit

2009-04-09T10:14:00.001-07:00

AS5145
12-Bit Programmable Magnetic Rotary Encoder
The AS5145 is a contact less magnetic rotary encoder for
accurate angular measurement over a full turn of 360 degrees.
It is a system-on-chip, combining integrated Hall elements,
analog front end and digital signal processing in a single device.
To measure the angle, only a simple two-pole magnet, rotating
over the center of the chip, is required. The magnet may be
placed above or below the IC.The absolute angle measurement
provides instant indication of the magnet’s angular position with
a resolution of 0.0879º = 4096 positions per revolution. This
digital data is available as a serial bit stream and as a PWM
signal.An internal voltage regulator allows the AS5145 to
operate at either 3.3V or 5V supplies.

Typical magnet (6x3mm) and magnetic field distribution

Daisy Chain Mode

The Daisy Chain mode allows connection of several
AS5145’s in series, while still keeping just one digital input
for data transfer (see “Data IN” in Figure 9). This mode is
accomplished by connecting the data output (DO; pin 9) to
the data input (PDIO; pin 8) of the subsequent device. The
serial data of all connected devices is read from the DO pin
of the first device in the chain. The length of the serial bit
stream increases with every connected device,
it is n * (18+1) bits: n= number of devices. e.g. 38 bit for two
devices, 57 bit for three devices, etcetc.

AS5145 Datasheet

Microcontroller Switch-Mode Battery Charger Circuit

2009-04-07T17:50:00.000-07:00

Microcontroller Battery Charger Circuit

In applications where a microcontroller is available, the
MAX1640/MAX1641 can be used as a low-cost battery
charger (Figure 5). The controller takes over fast
charge, pulse-trickle charge, charge termination, and
other smart functions. By monitoring the output voltage
at VOUT, the controller initiates fast charge (set D0 and
D1 high), terminates fast charge and initiates top-off
(set D0 high and D1 low), enters trickle charge (set D0
low and D1 high), or shuts off and terminates current
flow (set D0 and D1 low).
more pdf

MAX846A Li+ charger with charge timer and LED-status

outputs, controlled by an 8-pin Microcontroller

In this example, a small external µP enhances the MAX846A,
forming a complete desktop-charger system that includes
user-interface functions such as the LEDs in Figure (to indicate
the charge process and status). The MAX846A is designed for
this type of operation. Its auxiliary linear regulator and µP-reset
circuit (to support the external µC) reduces the cost of a typical
desktop-charger application.

Switch-Mode Battery Charger Circuit

2009-04-05T17:46:00.001-07:00

Fast, High Effi ciency, Standalone NiMH/NiCd Battery
Charging Circuit

Figure 1 shows a fast, 2A charger featuring the
high effi ciency LTC4011 550kHz synchronous buck
converter. The LTC4011 simplifi es charger design by
integrating all of the features needed to charge Ni-based
batteries, including constant current control circuitry,
charge termination, automatic trickle and top off
charge, automatic recharge, programmable timer,
PowerPath control and multiple status outputs. Such a
high level of integration lowers the component count,
enabling a complete charger to occupy less than 4cm2
of board area.

more

Battery Charger Delivers 2.5A With >96% Efficiency
Battery chargers are usually designed without regard for
efficiency, but the heat generated by low-efficiency
chargers can present a problem. For those applications,
the charger of Figure 1 delivers 2.5A with efficiency as
high as 96%. It can charge a battery of one to six cells
while operating from a car battery.

Figure 1. Modified feedback paths transform this switch-mode
power-supply circuit for notebook computers into a
high-efficiency battery charger.
more pdf

Switch Protection Design - Fast-Recovery Diodes

2009-03-31T18:58:00.000-07:00

Abstract
The number of fast recovery applications in high power systems
continues to grow leading to various dynamic constraints and
hence different diode designs and behaviours. Along with
conventional RC (“SCR-type”) and C (“GTO-type”) snubber
conditions, snubberless conditions in both IGBT and IGCT
applications are gaining ground at ever higher currents and
voltages (presently 6 kV). Within these two groups, the further
distinctions of “inductive” and “resistive” commutation di/dt must
be made for an optimal diode design. Diodes capable of high
reverse di/dt and dv/dt can today be realised thanks to controlled
life-time profiling which will be described here with both measured
and simulated results. As will also be explained, such “robust”
designs, though essential for snubberless operation, may be “less
robust” under snubbered conditions so that a clear understanding
of the application (Snubber, Free-Wheel, Clamp, Resistive or
Inductive di/dt) is required for the correct choice or design of a fast
recovery diode. The different diode commutation conditions will
be described and categorised and the optimal diode design
identified with supporting measurements and simulations.

Fig 2 “Inductive” commutation circuit fitted
with snubber and clamp

Traditionally the diode under consideration (in this case a
Free-Wheel Diode (FWD)) is fitted with a snubber and may also
be fitted with a clamp as shown in Fig. 2. Thus for the inductive
commutation circuit, we can define the additional sub-conditions
consisting of permutations of the snubbered/unsnubbered &
clamped/unclamped conditions whereby the snubber controls
the Duet’s dv/dt whereas the clamp controls its peak voltage.

More pdf

Mosfet Snubber Circuit in Flyback Converter Circuit

2009-03-29T18:55:00.000-07:00

Mosfet Protection in flyback Circuit

PKC-136

PEAK CLAMP

CHARACTERISTICS
VBR 160Vdc
VDRM 700Vdc
P 1.5W

Feature
- Protection of the Mosfet in flyback power supply
- TRANSIL™ and blocking diode in a single
package

BENEFITS

- Accurate voltage clamping regardless load
- Reduced current loop
- Reduced EMI emission
- High integration
- Fast assembly
- Reduced losses in stand by mode

PKC-136 datasheet pdf

Mosfet Snubber Circuit in Flyback Converter

Fig. 1 Typical flyback convertor with drain clamping circuits

ZenBlock
Zener with integrated blocking diode
Philips Semiconductors' new ZenBlockTM replaces
double-diode-, RCD- or RC-snubbers in flyback convertors.
The new components offer circuit designers the important
benefits of lower component count and board usage, reduced
EMI, optimal clamping at all loads and higher efficiency.

Introducing

The new ZenBlock combines the double diode snubber in one
package. This leads to the following advantages:
-Fewer components.
-Reduced circuit board space
-Lower EMI by reducing the drain clamp circuit length and
area.
-Optimal clamp performance at all loads (compared with RCD
and RC snubber)
-Higher efficiency at low loads (compared with RCD and RC
snubber)

ZenBlock datasheet pdf

Push-Pull Snubber Circuit

2009-03-27T18:52:00.000-07:00

Abstract
The DS3984, DS3988, DS3881, DS3882, DS3992, and DS3994
are cold-cathode fluorescent lamp (CCFL) controllers that use a
push-pull architecture to create the high-voltage AC waveforms
needed to drive the lamps. In a push-pull drive scheme, the
parasitic inductance of the step-up transformer, together with the
parasitic capacitance of the output of the n-channel power
MOSFETs, form a resonant circuit that can create unwanted
voltage spikes. High-voltage spikes can increase the stress on
the power MOSFETs and can also increase the electromagnetic
interference (EMI) created by the system. This application note
describes how to suppress the voltage spikes with a simple
resistor-capacitor (RC) network.

Push-pull drain snubber circuit.

more pdf

Design the MOSFET RCD Snubber Circuit

2009-03-25T19:11:00.001-07:00

When the power MOSFET is turned off, there is a high
voltage spike on the drain due to the transformer leakage
inductance. This excessive voltage on the MOSFET may
lead to an avalanche breakdown and eventually failure of the
FPS. Therefore, it is necessary to use an additional network
to clamp the voltage.

The RCD snubber circuit and MOSFET drain voltage
waveform are shown in Figure 10 and 11, respectively. The
RCD snubber network absorbs the current in the leakage
inductance by turning on the snubber diode (Dsn) once the
MOSFET drain voltage exceeds the voltage of node X as
depicted in Figure 10. In the analysis of snubber network, it
is assumed that the snubber capacitor is large enough that its
voltage does not change significantly during one switching
cycle. The snubber capacitor used should be ceramic or a
material that offers low ESR. Electrolytic or tantalum
capacitors are unacceptable due to these reason
Circuit diagram of the snubber network

The first step in designing the snubber circuit is to determine
the snubber capacitor voltage at the minimum input voltage
and full load condition (Vsn). Once Vsn is determined, the
power dissipated in the snubber network at the minimum
input voltage and full load condition is obtained as

where Ids-peak is specified in equation (8), fs is the FPS
switching frequency, Llk is the leakage inductance, Vsn is the
snubber capacitor voltage at the minimum input voltage and
full load condition, VRO is the reflected output voltage and
Rsn is the snubber resistor. Vsn should be larger than VRO
and it is typical to set Vsn to be 2~2.5 times VRO. Too small a
Vsn results in a severe loss in the snubber network as shown
in equation (23). The leakage inductance is measured at the
switching frequency on the primary winding with all other
windings shorted.
Then, the snubber resistor with proper rated wattage should
be chosen based on the power loss. The maximum ripple of
the snubber capacitor voltage is obtained as

where fs is the FPS switching frequency. In general, 5~10%
ripple of the selected capacitor voltage is reasonable.
The snubber capacitor voltage (Vsn) of equation (26) is for
the minimum input voltage and full load condition. When
the converter is designed to operate in CCM under this
condition, the peak drain current together with the snubber
capacitor voltage decrease as the input voltage increases as
shown in Figure 11. The peak drain current at the maximum
input voltage and full load condition (Ids2 peak) is obtained as

where Pin, and Lm are specified in equations (1) and (6),
respectively and fs is the FPS switching frequency.
The snubber capacitor voltage under maximum input voltage
and full load condition is obtained as

where fs is the FPS switching frequency, Llk is the primary
side leakage inductance, VRO is the reflected output voltage
and Rsn is the snubber resistor.

Figure 11. MOSFET drain voltage and snubber
capacitor voltage

From equation (26), the maximum voltage stress on the
internal MOSFET is given by

where VDC max is specified in equation (3). Check if Vds

max is below 85% of the rated voltage of the
MOSFET (BVdss) as shown in Figure 12. The voltage rating
of the snubber diode should be higher than BVdss. Usually,
an ultra fast diode with 1A current rating is used for the
snubber network.

In the snubber design in this section, neither the lossy
discharge of the inductor nor stray capacitance is considered.
In the actual converter, the loss in the snubber network is

Less than the designed value due to this effects

Source
Design Considerations for Battery Charger Using
Green Mode Fairchild Power Switch (FPSTM)

http://www.fairchildsemi.com/an/AN/AN-4138.pdf

Mosfet RCD Snubber Circuit Design

2009-03-09T18:03:00.000-07:00

Design Guidelines for RCD Snubber of Flyback Converters
Application Note AN-4147
Fairchild Semiconductor
Snubber design
The excessive voltage due to resonance between Llk1 and
COSS should be suppressed to an acceptable level by
an additional circuit to protect the main switch.

The RCD snubber
circuit and key waveforms are shown in Figures 2 and 3.
The RCD snubber circuit absorbs the current in the leakage
inductor by turning on the snubber diode (Dsn) when Vds
exceeds Vin+nVo. It is assumed that the snubber capacitance
is large enough that its voltage does not change during one
switching period.

When the MOSFET turns off and Vds is charged to Vin+nVo,
the primary current flows to Csn through the snubber diode
(Dsn). The secondary diode turns on at the same time.
Therefore, the voltage across Llk1 is Vsn-nVo. The slope of
isn is as follows:
more(pdf)

Snubber Circuits Suppress Voltage Transient Spikes in
Multiple Output DC-DC Flyback Converter Power Supplies
RCD Voltage Snubber
This snubber is applicable to rate-of-rise voltage control
and/or clamping. The presence of the diode in the
configuration makes this a polarized snubber. The two
possible configurations for this resistor-capacitor-diode
(RCD) snubber are shown in Figure 2. The configuration
shown in Figure 2A can only act as a voltage clamp.
The variation shown in Figure 2B is applicable to either
rate-of-rise control or clamping of the drain voltage of
the switch.

RCD Clamp
In the clamp mode the purpose of the snubber is to
clamp the voltage during turn-off at the drain of the
MOSFET. The parallel RC circuit may be returned to
ground or to a voltage other than ground (i.e., input voltage
if the drain can go above input voltage) since this will
reduce the power dissipation in the resistor. The MOSFET
switch itself will have to sustain the peak power dissipation
during turn-off. The value of the capacitor, CCLAMP,
and resistor, RCLAMP, is based on the energy stored in
the parasitic inductance, as this energy must be
discharged into the RC network during each cycle.
The voltage across the capacitor and resistor sets the
Clamp voltage, VCLAMP.

Rate-of-Rise Control RCD Snubber
When the RCD snubber is used to control the rate of
voltage rise at the MOSFET drain, the capacitor must be
completely charged and discharged during each cycle to
be able to control the rate-of-rise of the drain voltage.
The RC time constant of the snubber should, therefore,
be much smaller than the switching period (consider the
effect of duty cycle on pulse width). Typically, the time
constant should be about 1/10th the switching period.
When the switch turns off, the inductor current is diverted
through the snubber diode to charge the capacitor to
the rail. At that time, it is expected that the output rectifier
will turn on.

more(pdf)

MAGNETIC SNUBBER FOR 200W PFC
WITH UNIVERSAL MAINS
In high voltage continuous mode boost converters,
a significant part of the power mosfet switching
losses is related to the turn-on edge.
In fact, at turn on, the power mosfet has to sustain
both the boost diode reverse recovery and
the stray capacitances associated energies.
Moreover, the additional peak current due to the
recovery of the diode can be significantly high, in
particular at high temperature, thus increasing the
high frequency noise, the E.M.I. filter requirements
and reducing efficiency.
The turn on peak current, generating all the
above mentioned problems, has been dramatically
reduced by using the magnetic snubber we
propose at Fig. 1b.
The concept of this snubber is to reduce (and
control) the turn-on di/dt of the mosfet to the most
convenient value, considering the voltages and
switching frequency applied to the system.

Voltage Snubber

Magnetic snubber

more(pdf)

Design the MOSFET RCD snubber circuit

Inductor Design

2009-03-05T17:07:00.000-08:00

Filter inductor design constraints
Objective:
Design inductor having a given inductance L,
which carries worst-case current Imax without saturating,
and which has a given winding resistance R, or,
equivalently

Index
- Assumed filter inductor geometry
- Constraint: maximum flux density
- Constraint: Inductance
- Constraint: Winding area
- The window utilization factor Ku
- also called the “fill factor”
- Winding resistance
- The core geometrical constant Kg
- Core geometrical constant Kg
- A step-by-step procedure

more (pdf)

INDUCTOR DESIGN in SWITCHING REGULATORS
Technical Bulletin
Better efficiency, reduced size, and lower costs have combined to
make the switching regulator a viable method for converting unfiltered
DC input voltages into regulated DC outputs. This brochure describes
the switching regulator and presents design information. In particular,
MAGNETICS® Ferrite and Molypermalloy Powder cores used for
the power inductor are highlighted.

DESCRIPTION

A typical circuit consists of three parts: transistor switch, diode
clamp, and an LC filter. An unregulated DC voltage is applied to
the transistor switch which usually operates at a frequency of 1 to 50
kilohertz. When the switch is ON, the input voltage, Ein, is applied to
the LC filter, thus causing current through the inductor to increase;
excess energy is stored in the inductor and capacitor to maintain
output power during the OFF time of the switch. Regulation is
obtained by adjusting the ON time, ton, of the transistor switch, using
a feedback system from the output. The result is a regulated DC
output,

index
- COMPONENT SELECTION
- INDUCTOR DESIGN
- CORE SELECTION PROCEDURE
- DESIGN EXAMPLE

more(pdf)

Switching Regulator Inductor Design
COILTRONICS Application Notes Magnetics
In switching regulator applications the inductor is used as
an energy storage device, when the semiconductor
switch is on the current in the inductor ramps up and
energy is stored. When the switch turns off this energy is
released into the load, the amount of energy stored is
given by;
Energy = 1/2L.I2 (Joules) (1)
Where L is the inductance in Henrys and I is the peak
value of inductor current.
The amount by which the current changes during a
switching cycle is known as the ripple current and is
defined by the equation;
V1 = L.di/dt (2)
Where V1 is the voltage across the inductor, di is the
ripple current and dt is the duration for which the voltage
is applied. From this we can see that the value of ripple
current is dependent upon the value of inductance.
Choosing the correct value of inductance is important in
order to obtain acceptable inductor and output capacitor
sizes and sufficiently low output voltage ripple.

Index
- Inductor Selection for Buck Converters
- Inductor Selection for Boost Converters
- Inductor Selection for Buck-Boost Converters

more(pdf)

Gate Drive for step-down switching regulator

Gate Drive for step-down switching regulator

2009-03-02T17:17:00.000-08:00

CDV/DT INDUCED TURN-ON IN SYNCHRONOUS BUCK
REGULATORS
Abstract
Cdv/dt induced turn-on of the synchronous MOSFET deteriorates
performance in synchronous buck regulators. We will discuss this
problem and provide several solutions that can reduce the effects.
BIPOLAR OR CMOS GATE DRIVER?
An in-circuit waveform showing the Cdv/dt induced
turn-on effect at Q2 gate is demonstrated in Figure 7. The
gate drive circuit might further deteriorate this Cdv/dt
induced turn-on problem. It is clear in Figure 7 that the
gate driver can only pull the gate voltage of Q2 down to
0.7V, instead of zero, when Q2 is turned off. However, the
Cdv/dt induced voltage is sitting on top of this turn-off
gate voltage and makes Q2 more vulnerable to the Cdv/dt
induced turn-on problem. The gate driver used in Figure 7
is created by a bipolar process.

http://www.irf.com/technical-info/whitepaper/syncbuckturnon.pdf

“Shoot-through” in Synchronous Buck Converters
Abstract
The synchronous buck circuit is in widespread use to
provide “point of use” high current, low voltage
power for CPU’s, chipsets, peripherals etc. In the
synchronous buck converter, the power stage has a
“high-side” (Q1 below) MOSFET to charge the
inductor, and a “Low-side” MOSFET which replaces
a conventional buck regulator’s “catch diode” to
provide a low-loss recirculation path for the inductor
current.

Shoot-through is defined as the condition when both
MOSFETs are either fully or partially turned on,
providing a path for current to “shoot through” from
VIN to GND. To minimize shoot-through,
synchronous buck regulator IC’s employ one of two
techniques to ensure “break before make” operation
of Q1 and Q2 to minimize shoot-through:

1. Fixed “dead-time”: A MOSFET is turned off,
then a fixed delay is provided before the lowside
is turned on. This circuit is simple and
usually effective, but suffers from its lack of
flexibility if a wide range of MOSFET gate
capacitances are to be used with a given
controller. Too long a dead-time means high
conduction losses. Too short a dead time can
cause shoot-through. A fixed dead-time
typically must err on the “too long” side to allow
high CGS MOSFETs to fully discharge before
turning on the complementary MOSFET.

2. Adaptive gate drive: This circuit looks at the
VGS of the MOSFET that’s being driven off to
determine when to turn on the complementary
MOSFET. Theoretically, adaptive gate drives
produce the shortest possible dead-time for a
given MOSFET without producing shootthrough.
In practice, a combination of adaptive and fixed
produces the best results, and is typically what is in
today’s PWM controllers and gate drivers as shown
in Figure 2

http://www.fairchildsemi.com/an/AN/AN-6003.pdf

A New Hybrid Gate Drive Scheme for High
Frequency Buck Voltage Regulators
Abstract
This paper presents a new hybrid drive scheme
for a synchronous buck voltage regulator (VR). The
proposed current-source driver is used to drive the control
MOSFET to achieve fast switching speed and reduce the
switching loss significantly due to the parasitic inductance in
addition to gate energy recovery. Conventional voltage
driver is used for synchronous rectifier (SR) MOSFET for
its simplicity and good immunity and alleviation of dv/dt
effect. The experimental results prove the advantages of the
new drive scheme and a significant efficiency improvement
has been achieved. At 1.3 V output, the new driver improves
the efficiency from 82.8% using a conventional driver to
85.6% (an improvement of 2.8%) at 20 A, and at 25 A, from
80.5% to 83.0% (an improvement of 2.5%). The new drive
can also be integrated into a standard drive integrated
circuit (IC) and replace the conventional voltage drive IC
directly. Overall, the new driver scheme is very promising
from the standpoints of both performance and costeffectiveness.

Figure 2 shows the buck converter with the proposed
hybrid drive circuit. The key waveforms are shown in
Figure 3. Essentially, the new high-side current-source
driver is used for the control MOSFET to achieve fast
switching transition. It consists of two driver MOSFETs
S1 and S2, a bipolar transistor pair S3 and S4, the resonant
inductor Lr, the bootstrap capacitor Cf , diode Df and the
blocking capacitor Cb. Vc are the drive voltages. Cgs1 and
Cgs2 are the input gate capacitors of MOSFETs Q1 and Q2
respectively. S1 and S2 are switched out of phase with
complimentary control respectively.

Switching Regulator by Hysteretic PFET Buck Controller

2009-02-27T17:12:00.000-08:00

LM3485/LM3485Q
Hysteretic PFET Buck Controller
General Description
The LM3485 is a high efficiency PFET switching regulator
controller that can be used to quickly and easily develop a
small, low cost, switching buck regulator for a wide range of
applications. The hysteretic control architecture provides for
simple design without any control loop stability concerns using
a wide variety of external components. The PFET architecture
also allows for low component count as well as ultralow
dropout, 100% duty cycle operation. Another benefit is
high efficiency operation at light loads without an increase in
output ripple.
Current limit protection is provided by measuring the voltage
across the PFET’s RDS(ON), thus eliminating the need for a
sense resistor. The cycle-by-cycle current limit can be adjusted
with a single resistor, ensuring safe operation over a range
of output currents.

Features
- Easy to use control methodology
- No control loop compensation required
- 4.5V to 35V wide input range
- 1.242V to VIN adjustable output range
- High Efficiency 93%
- ฑ1.3% (ฑ2% over temp) internal reference
- 100% duty cycle
- Maximum operating frequency > 1MHz
- Current limit protection
- MSOP-8
- LM3485Q is AEC-Q100 Grade 1 qualified and are
manufactured on an Automotive Grade Flow

LM3485 Datasheet Pdf

Circuit PCB

5A switching regulator with Adjustable Current Limit

Switching Regulator by High-Side N-Channel Controller

2009-02-24T17:53:00.001-08:00

LM3477
High Efficiency High-Side N-Channel Controller for
Switching Regulator
Description
The LM3477/A is a high-side N-channel MOSFET switching
regulator controller. It can be used in topologies requiring a
high side MOSFET such as buck, inverting (buck-boost) and
zeta regulators. The LM3477/A’s internal push pull driver
allows compatibility with a wide range of MOSFETs. This, the
wide input voltage range, use of discrete power components
and adjustable current limit allows the LM3477/A to be optimized
for a wide variety of applications.
The LM3477/A uses a high switching frequency of 500kHz to
reduce the overall solution size. Current-mode control requires
only a single resistor and capacitor for frequency
compensation. The current mode architecture also yields
superior line and load regulation and cycle-by-cycle current
limiting. A 5µA shutdown state can be used for power savings
and for power supply sequencing. Other features include
internal soft-start and output over voltage protection.
The internal soft-start reduces inrush current. Over voltage
protection is a safety feature to ensure that the output voltage
stays within regulation.
The LM3477A is similar to the LM3477. The primary difference
between the two is the point at which the device
transitions into hysteretic mode. The hysteretic threshold of
the LM3477A is one-third of the LM3477.

Features
- 500kHz switching frequency
- Adjustable current limit
- 1.5% reference
- Thermal shutdown
- Frequency compensation optimized with a single
capacitor and resistor
- Internal softstart
- Current mode operation
- Undervoltage lockout with hysteresis
- 8-lead Mini-SO8 (MSOP-8) package

LM3477 Datasheet Pdf

Switching Regulator by Hysteretic PFET Buck Controller

5A switching regulator with Adjustable Current Limit

2009-02-22T16:57:00.000-08:00

LM2679
5A Step-Down Voltage Regulator
with Adjustable Current Limit

Description
The LM2679 series of regulators are monolithic integrated
circuits which provide all of the active functions for a stepdown
(buck) switching regulator capable of driving up to 5A
loads with excellent line and load regulation characteristics.
High efficiency (>90%) is obtained through the use of a low
ON-resistance DMOS power switch. The series consists of
fixed output voltages of 3.3V, 5V and 12V and an adjustable
output version.
The SIMPLE SWITCHER concept provides for a complete
design using a minimum number of external components. A
high fixed frequency oscillator (260KHz) allows the use of
physically smaller sized components. A family of standard
inductors for use with the LM2679 are available from several
manufacturers to greatly simplify the design process.
Other features include the ability to reduce the input surge
current at power-ON by adding a softstart timing capacitor to
gradually turn on the regulator. The LM2679 series also has
built in thermal shutdown and resistor programmable current
limit of the power MOSFET switch to protect the device and
load circuitry under fault conditions. The output voltage is
guaranteed to a ±2% tolerance. The clock frequency is
controlled to within a ±11% tolerance.

Features
- Efficiency up to 92%
- Simple and easy to design with (using off-the-shelf
external components)
- Resistor programmable peak current limit over a range
of 3A to 7A.
- 120 mΩ DMOS output switch
- 3.3V, 5V and 12V fixed output and adjustable (1.2V to
37V ) versions
- ±2%maximum output tolerance over full line and load
conditions
- Wide input voltage range: 8V to 40V
- 260 KHz fixed frequency internal oscillator
- Softstart capability
- −40 to +125°C operating junction temperature range

LM2679 Datasheet Pdf

dual step-down switching regulator circuit

dual step-down switching regulator circuit

2009-02-19T16:47:00.000-08:00

The output voltages
OUT1 0.9 V to 5.5 V
OUT2 0.9 V to 3.3 V

PM6680
No Rsense dual step-down controller with adjustable voltages
for notebook system power

Description
PM6680 is a dual step-down controller
specifically designed to provide extremely high
efficiency conversion, with lossless current
sensing technique. The constant on-time
architecture assures fast load transient response
and the embedded voltage feed-forward provides
nearly constant switching frequency operation. An
embedded integrator control loop compensates
the DC voltage error due to the output ripple.
Pulse skipping technique increases efficiency at
very light load. Moreover a minimum switching
frequency of 33kHz is selectable to avoid audio
noise issues. The PM6680 provides a selectable
switching frequency, allowing three different
values of switching frequencies for the two
switching sections.

Features
- 6 V to 28 V input voltage range
- Adjustable output voltages
- 5 V always voltage available deliver 100 mA
peak current
- 1.237 V ± 1% reference voltage available
- Lossless current sensing using low side
MOSFETs RDS(on)
- Negative current limit
- Soft-start internally fixed at 2ms
- Soft output discharge
- Latched OVP and UVP
- Selectable pulse skipping at light loads
- Selectable minimum frequency (33 kHz) in
pulse skip mode
- 4 mW maximum quiescent power
- Independent power good signals
- Output voltage ripple compensation

PM6680 Datasheet Pdf

10A stepdown switching regulator circuit

10A stepdown switching regulator circuit

2009-02-17T16:50:00.001-08:00

TYPICAL PERFORMANCES (using evaluation board)
n = 83% (Vi = 35V ; Vo = VREF ; Io = 10A ; fSW = 200KHz)
Vo RIPPLE = 30mV (at 10A) with output filter capacitor
Line regulation = 5mV (Vi = 15 to 50V)
Load regulation = 15mV (Io = 2 to 10A)
For component values, refer to test circuit part list.

L4970A
DESCRIPTION
The L4970A is a stepdown monolithic power
switching regulator delivering

Frature
- 10A OUTPUT CURRENT
- 5.1V TO 40V OUTPUT VOLTAGE RANGE
- 0 TO 90% DUTY CYCLE RANGE
- INTERNAL FEED-FORWARD LINE REGULATION
- INTERNAL CURRENT LIMITING
- PRECISE 5.1V ± 2% ON CHIP REFERENCE
- RESET AND POWER FAIL FUNCTIONS
- SOFT START
- INPUT/OUTPUT SYNC PIN
- UNDER VOLTAGE LOCK OUT WITH HYSTERETIC
- TURN-ON
- PWM LATCH FOR SINGLE PULSE PER PERIOD
- VERY HIGH EFFICIENCY
- SWITCHING FREQUENCY UP TO 500KHz
- THERMAL SHUTDOWN
- CONTINUOUS MODE OPERATION

L4970A Datasheet Pdf

Power Amplifier Circuit

2009-02-16T16:43:00.000-08:00

Single Supply High Power Amplifier Circuit

30W Bridge Amplifier Circuit

BTL stereo car radio power amplifier

Stereo Amplifier with Mute and Stand-by Circuit

125W Class D Audio Power Amplifier

Single Supply 68W Audio Power Amplifier Circuit

stereo headphone audio amplifier circuit

stereo headphone audio amplifier circuit

2009-02-16T16:34:00.000-08:00

LM4980
2 Cell Battery, 1mA, 42mW Per Channel High Fidelity
Stereo Headphone Audio Amplifier for MP3 players
Description
The LM4980 is a stereo headphone audio amplifier, which
when connected to a 3.0V supply, delivers 42mW to a 16Ω
load with less than 1% THD+N. With the LM4980 packaged
in the SD package, the customer benefits include low profile
and small size. This package minimizes PCB area and maximizes
output power.
The LM4980 features circuitry that significantly reduces output
transients (“clicks” and “pops”) while driving headphones
during device turn-on and turn-off without costly external
additional circuitry. The LM4980 also includes an externally
controlled low-power consumption active-low shutdown
mode, and thermal shutdown. Boomer audio power amplifiers
are designed specifically to use few external components
and provide high quality output power in a surface
mount package.
Specifications
- Output power
(RL = 16Ω, VDD = 3.0V, THD+N = 1%) 42mW (typ)
- Quiescent current (VDD = 3V) 1mA (typ)
- Micropower shutdown current 0.1µA (typ)
- Supply voltage operating range 1.5V <>

VDD = 3.0V 90dB (typ) - PSRR @ 217Hz, VDD = 3.0V 100dB (typ)

Features

- 2-cell 1.5V to 3.3V battery operation

- Unity-gain stable

- “Click and pop” suppression circuitry for shutdown

and power on/off transient with headphone loads

- Active low micro

-power shutdown

- Thermal shutdown protection circuitry

LM4980 Datasheet Pdf

Single Supply 68W Audio Power Amplifier Circuit

2009-02-13T17:16:00.001-08:00

LM3886 Overture™ Audio Power Amplifier Series
High-Performance 68W Audio Power Amplifier w/Mute
General Description
The LM3886 is a high-performance audio power amplifier
capable of delivering 68W of continuous average power to a
4Ω load and 38W into 8Ω with 0.1% THD+N from 20Hz–20kHz.
The performance of the LM3886, utilizing its Self Peak Instantaneous
Temperature (°Ke) (SPiKe™) protection circuitry,
puts it in a class above discrete and hybrid amplifiers
by providing an inherently, dynamically protected Safe Operating
Area (SOA). SPiKe protection means that these
parts are completely safeguarded at the output against overvoltage,
undervoltage, overloads, including shorts to the
supplies, thermal runaway, and instantaneous temperature peaks.
The LM3886 maintains an excellent signal-to-noise ratio of
greater than 92dB with a typical low noise floor of 2.0µV. It
exhibits extremely low THD+N values of 0.03% at the rated
output into the rated load over the audio spectrum, and
provides excellent linearity with an IMD (SMPTE) typical
rating of 0.004%.
Features
- 68W cont. avg. output power into 4Ω at VCC = ±28V
- 38W cont. avg. output power into 8Ω at VCC = ±28V
- 50W cont. avg. output power into 8Ω at VCC = ±35V
- 135W instantaneous peak output power capability
- Signal-to-Noise Ratio ≥ 92dB
- An input mute function
- Output protection from a short to ground or to the
supplies via internal current limiting circuitry
- Output over-voltage protection against transients from
inductive loads
- Supply under-voltage protection, not allowing internal
biasing to occur when VEE + VCC ≤ 12V, thus
eliminating turn-on and turn-off transients
- 11-lead TO-220 package
- Wide supply range 20V - 94V

LM3886 Datasheet Pdf

125W Class D Audio Power Amplifier

2009-02-11T17:09:00.001-08:00

The IC combination of the LM4651 driver and the LM4652
power MOSFET provides a high efficiency, Class D subwoofer
amplifier solution.
- Output Power, 1% THD 125W
- Load Impedance 4Ω
- Input Signal level 3V RMS (max)
- Input Signal Bandwidth 10Hz − 150Hz
- Ambient Temperature 50°C (max)
- Supply voltage +- 20V

LM4651
The LM4651 is a fully integrated conventional pulse width
modulator driver IC. The IC contains short circuit, under
voltage, over modulation, and thermal shut down protection
circuitry. The LM4651also contains a standby function which
shuts down the pulse width modulation minimizing supply
current. The LM4652 is a fully integrated H-bridge power
MOSFET IC in a TO-220 power package. The LM4652 has a
temperature sensor built in to alert the LM4651 when the die
temperature of the LM4652 exceeds the threshold. Together,
these two IC’s form a simple, compact high power audio
amplifier solution complete with protection normally seen
only in Class AB amplifiers. Few external components and
minimal traces between the IC’s keep the PCB area small
and aids in EMI control.

Features
- Conventional pulse width modulation.
- Externally controllable switching frequency.
- 50kHz to 200kHz switching frequency range.
- Integrated error amp and feedback amp.
- Turn−on soft start and under voltage lockout.
- Over modulation protection (soft clipping).
- Externally controllable output current limiting and
thermal shutdown protection.
- Self checking protection diagnostic.

LM4651 Datasheet Pdf

Stereo Amplifier with Mute and Stand-by Circuit

2009-02-08T16:35:00.000-08:00

SINGLE SUPPLY

TDA7499
6 + 6W STEREO AMPLIFIER WITH MUTE AND STAND-BY
DESCRIPTION
The UTC TDA7499 is class AB dual Audio Power Amplifier
and designed for high quality sound application as Hi-Fi
music centers and stereo TV sets.

FEATURES
- Wide supply voltage range up to ±18V
- 6 + 6W @ THD =10%, RL = 8Ω, VS = +14V
- No POP at Turn-On/Off
- MUTE (POP free)
- STAND-BY feature (Low Iq)
- Short circuit protection to GND
- Thermal overload protection

MUTE/STAND-BY FUNCTION
MUTE/STAND-BY function is assembled at pin 5 and to control
the amplifier status by two different thresholds,referred to +VS.
-When Vpin5 higher than = +VS - 2.5V the amplifier is in Stand-by
mode and the final stage generators are off
-When Vpin5 is between +VS - 2.5V and +VS - 6V the final stage
current generators are switched on and the amplifier is in mute mode
-When Vpin5 is lower than +VS - 6V the amplifier is play mode.

TDA7499 Datasheet Pdf

BTL stereo car radio power amplifier

2009-02-07T18:05:00.001-08:00

TDA1557Q
2 x 22 W BTL stereo car radio power
amplifier with speaker protection
The TDA1557Q is a monolithic integrated class-B output
amplifier in a 13-lead single-in-line (SIL) plastic power
package. The device contains 2 x 22 W amplifiers in BTL
configuration and has been primarily developed for car
radio applications.

FEATURES
- Requires very few external components
- High output power
- Low offset voltage at output
- Fixed gain
- Good ripple rejection
- Mute/stand-by switch
- Load dump protection
- AC and DC short-circuit-safe to ground and VP
- Thermally protected
- Reverse polarity safe
- Capability to handle high energy on outputs (VP = 0)
- Protected against electrostatic discharge
- No switch-on/switch-off plop
- Flexible leads
- Low thermal resistance.

TDA1557Q Datasheet Pdf

Stepper motor driver circuit

2009-02-04T17:00:00.000-08:00

Stepper Motor Data

Stepper Motor Driver Circuit

30W Bridge Amplifier Circuit

2009-02-04T16:47:00.000-08:00

TDA2040
20W Hi-Fi AUDIO POWER AMPLIFIER
DESCRIPTION
The TDA2040 is a monolithic integrated circuit in
Pentawatt[ package,intended for use as an audio
class AB amplifier. Typically it provides22W output
power (d = 0.5%) at Vs = 32V/4W . The TDA2040
provides high output current and has very low
harmonic and cross-over distortion. Further the
device incorporates a patented short circuit protection
system comprising an arrangement for automaticallylimiting
the dissipatedpowersoas to keep
the working point of the output transistors within
their safe operating area. A thermal shut-down
system is also included.

ABSOLUTE MAXIMUM RATINGS
Vs Supply Voltage ± 20 V
Vi Input Voltage Vs
Vi Differential Input Voltage ± 15 V
Io Output Peak Current (internally limited) 4 A
Ptot Power Dissipation at Tcase = 75 °C 25 W
Tstg, Tj Storage and Junction Temperature – 40 to + 150 °C

TDA2040 Datasheet Pdf

Single Supply High Power Amplifier Circuit

2009-02-02T16:51:00.000-08:00

TDA2030A

18W Hi-Fi AMPLIFIER AND 35W DRIVER
DESCRIPTION
The TDA2030A is a monolithic IC in Pentawatt Ò
package intended for use as low frequency class
AB amplifier.
With VS max = 44V it is particularly suited for more
reliable applications without regulated supply and
for 35W driver circuits using low-cost complementary
pairs.
The TDA2030A provides high output current and
has very low harmonic and cross-over distortion.
Further the device incorporates a short circuit protection
system comprising an arrangement for
automatically limiting the dissipated power so as to
keep the working point of the output transistors
within their safe operating area. A conventional
thermal shut-down system is also included.

SHORT CIRCUIT PROTECTION
The TDA2030A has an original circuit which limits
the current of the output transistors. This function
can be considered as being peak power limiting
rather than simple current limiting. It reduces the
possibility that the device gets damaged during an
accidental short circuit from AC output to ground.
THERMAL SHUT-DOWN
The presence of a thermal limiting circuit offers the
following advantages:
1. An overload on the output (even if it is
permanent), or an above limit ambient
temperature can be easily supported since the
Tj cannot be higher than 150 C.

2. The heatsink can have a smaller factor of safety
compared with that of a conventional circuit.
There is no possibility of device damage due to
high junction temperature. If for any reason, the
junction temperature increases up to 150 C,
the thermal shut-down simply reduces the
power dissipat ion and the current
consumption.

TDA2030A Datasheet Pdf

High Current Microstep Stepper Motor Driver

2009-01-30T16:37:00.000-08:00

High Current Microstep Stepper Motor Driver
with protection
The TMC236 / TMC236A (1) is a dual full bridge driver IC for bipolar
stepper motor control applications. It is realized in a HVCMOS
technology combined with Low-RDS-ON high efficiency MOSFETs
(pat. pend.). It allows to drive a coil current of up to 1500mA even at
high environment temperatures. Its low current consumption and high
efficiency together with the miniature package make it a perfect
solution for embedded motion control and for battery powered devices.
The low power dissipation makes the TMC236 an optimum choice for
drives, where a high reliability is desired. Internal DACs allow
microstepping as well as smart current control. The device can be
controlled by a serial interface (SPI™i) or by analog / digital input
signals. Short circuit, temperature, undervoltage and overvoltage
protection are integrated.

Feature

• Control via SPI with easy-to-use 12 bit protocol or external
analog / digital signals
• Short circuit, overvoltage and overtemperature protection integrated
• Status flags for overcurrent, open load, over temperature, temperature
pre-warning, undervoltage
• Integrated 4 bit DACs allow up to 16 times microstepping via SPI
(can be expanded to 64 microsteps)
• Any resolution via analog control
• Mixed decay feature for smooth motor operation
• Slope control user programmable to reduce electromagnetic emissions
• Chopper frequency programmable via a single capacitor or external clock
• Current control allows cool motor and driver operation
• Internal open load detector
• 7V to 34V motor supply voltage (A-type)
• Up to 1500mA output current and more than 800mA at 105°C
• 3.3V or 5V operation for digital part
• Low power dissipation via low RDS-ON power stage
• Standby and shutdown mode available

TMC236 Datasheet pdf

Precision Microstepping Driver Circuit

2009-01-28T16:11:00.001-08:00

PBM 3960 is a dual 7-bit+sign, Digital-to-Analog Converter (DAC)
Especially developed to be used together with the PBL 3771,
Precision Stepper Motor driver in micro-stepping applications.
The circuit has a set of input registers connected to an 8-bit data port
for easy interfacing directly to a microprocessor. Two registers are
used to store the data for each seven-bit DAC, the eighth bit being a
sign bit (sign/ magnitude coding). A second set of registers are used
for automatic fast/slow current decay control in conjunction with
the PBL 3771, a feature that greatly improves highspeed micro-stepping
performance. The PBM 3960 is fabricated in a high-speed CMOS
process.

Key Features
- Analog control voltages from 3 V down to 0.0 V.
- High-speed microprocessor interface.
- Automatic fast/slow current decay control.
- Full-scale error ±1 LSB.
- Interfaces directly with TTL levels and CMOS devices.
- Fast conversion speed, 3 ms.
- Matches PBL 3771.

PBM 3960 Datasheet pdf

Stepper motor driver circuit Index

Microstepping Data

2009-01-26T16:40:00.000-08:00

Microstepping of Stepper Motors
Let's now look at what current ratios are needed to produce a particular
step angle. The Microstep angle can be graphically represented with
a Phasor Diagram. (See diagram below) The X and Y axis indicate
the current level in two respective coils A, B. A vector (ray from origin
to coordinate X,Y) shows the resultant angle and Torque (magnitude
of the vector) when some current is applied to both coils. Keep in mind
that this diagram shows the 'sub-angle' between natural whole steps
(poles) of the motors. On a typical 200 step per revolution motor this
is 1.8 degrees. The graph below is a representation of how that angle
can be further sub-divided.
http://www.stepperworld.com/Tutorials/pgMicrostepping.htm

Microstepping Tutorial
If the controller is designed with the capability to control the magnitude
of the current in each winding, then microstepping can be implemented.
The phase diagrams below all show different implementations of "divide
by 4" microstepping. Note that it is the phasor angle (not it's length) that
determines the microstep position.

http://www.zaber.com/wiki/Microstepping_Tutorial

Stepping Motor Physics
Microstepping allows even smaller steps by using different currents
through the two motor windings

For a two-winding variable reluctance or permanent magnet motor,
assuming nonsaturating magnetic circuits, and assuming perfectly
sinusoidal torque versus position curves for each motor winding
http://www.suc-tech.com/technology/stepcontrol2.htm

Variable-reluctance Stepper Motors

2009-01-23T16:31:00.000-08:00

Variable-reluctance (VR) Stepper Motors

The variable-reluctance (VR) stepper motor differs from the PM
stepper in that it has no permanent-magnet rotor and no residual
torque to hold the rotor at one position when turned off. When the
stator coils are energized, the rotor teeth will align with the energized
stator poles. This type of motor operates on the principle of minimizing
the reluctance along the path of the applied magnetic field. By
alternating the windings that are energized in the stator, the stator field
changes, and the rotor is moved to a new position.
http://zone.ni.com/devzone/cda/ph/p/id/287#toc2

Variable reluctance stepper

The drive waveforms for the 3-φ stepper can be seen in the
“Reluctance motor” section. The drive for a 4-φ stepper is shown in
Figure . Sequentially switching the stator phases produces a rotating
magnetic field which the rotor follows. However, due to the lesser
number of rotor poles, the rotor moves less than the stator angle for
each step.
more

Switched Reluctance Motor

switched reluctance (also known as variable reluctance) motor has
no permanent magnets or brushes. Coils connected in series around
a pair of opposite stator poles are energised by a DC current to create
lines of magnetic flux. This causes a pair of teeth on the iron rotor to
align themselves with the stator poles. This sequence is continued around
the stator poles causing the rotor to rotate. Suitable for high torque and
high speed applications
more

Stepper Motor Data 3

2009-01-20T16:47:00.000-08:00

How To Select A Step Motor Driver

A step motor driver provides precisely controllable speed and positioning.
The motor increments a precise amount with each control pulse easily
converting digital information to exact incremental rotation without the
need for feedback devices such as tachometers or encoders. Because
the system is open loop, the problems of feedback loop phase shift and
resultant instability, common with servo drives, are eliminated.
Load characteristics, performance requirements, and mechanical design
including coupling techniques must be thoroughly considered before
the designer can effectively select the most suitable motor and driver
combination for an application.
http://www.anaheimautomation.com/intro.htm

Torque-angle curves for the stepping motor

(a) permanent-magnet rotor and (b) variable-reluctance rotor.

currents. Reversing the phase currents will cause the rotor to reverse
its orientation. This is in contrast to VRM configuration with
a ferromagnetic rotor, in which two rotor positions are equally stable
for any particular set of phase currents, and hence the rotor position
cannot be determined uniquely. Permanent-magnet stepping motors
are also unlike their VRM counterparts in that torque tending to align
the rotor with the stator poles will be generated even when there is
no excitation applied to the phase windings. Thus the rotor will have
preferred unexcited rest positions, a fact which can be used to advantage
in some applications.
http://vocw.edu.vn/content/m10680/latest/

Stepper Motor Data 2

2009-01-18T16:48:00.001-08:00

Types of Stepper Motors
A stepper, or stepping motor converts electronic pulses into
proportionate mechanical movement. Each revolution of
the stepper motor's shaft is made up of a series of discrete individual
steps. A step is defined as the angular rotation produced by the output
shaft each time the motor receives a step pulse.
The most popular types of stepper motors are permanent-magnet
(PM) and variable reluctance (VR).
http://zone.ni.com/devzone/cda/ph/p/id/287

Half Stepping

The motor can also be "half stepped" by inserting an off state
between transitioning phases.This cuts a stepper's full step angle
in half.For example,a 90° stepping motor would move 45 on each
half step,
more

Typical Stepping Sequence for a Four Phase Stepper Motor

A change in the coil states (ie. changing from state 2 to state 3 as
shown above) results in a single step of the motor shaft. Direction
is easily controlled by running through the above sequence either
forward or backward. It should also be noted that the coils A and A'
are always oppositely charged, as are coils B and B'. By inverting
the signals going to coils A and B, the corresponding signals A' and B'
can be attained. Thus, only two control lines are required to place
the motor into any one of the 4 possible states.
more

Stepper Motor Data 1

2009-01-15T16:55:00.000-08:00

program shows the basic operation of the stepper motors

This program shows the basic operation of the unipolar and
bipolar stepper motors. In addition there are demos of a translator
, oscillator and indexer.
http://www.wimb.net/index.php?s=delphi&page=6

Basic theory of Stepping Motors

Stepping motors are electromagnetic, rotary, incremental devices
which convert digital pulses into mechanical rotation. The amount
of rotation is directly proportional to the number of pulses and the
speed of rotation is relative to the frequency of those pulses.

Static or holding torque - displacement characteristic
The characteristic of static (holding) torque - displacement is best
explained using an electro-magnet and a single pole rotor . In
the example the electro-magnet represents the motor stator and is
energized with it's north pole facing the rotor
http://www.sapiensman.com/step_motor/

Stepper Motors: Principles of Operation

Permanent Magnet stepper motors incorporate a permanent magnet
rotor, coil windings and magnetically conductive stators. Energizing
a coil winding creates an electromagnetic field with a north and south
pole .
http://www.pc-control.co.uk/step-motor.htm

Microstep Stepper motor driver circuit

2009-01-12T16:33:00.000-08:00

Half-step, full-step and microstep Stepper motor driver

The L6219 is a bipolar monolithic integrated
circuits intended to control and drive both winding
of a bipolar stepper motor or bidirectionally control
two DC motors.
The L6219 with a few external components form a
complete control and drive circuit for LS-TTL or
microprocessor controlled stepper motor system.
The power stage is a dual full bridge capable of
sustaining 46V and including four diodes for
current recirculation.

Features
- Able to drive both windings of bipolar stepper
motor
- Output current up to 750 mA each winding
- Wide voltage range: 10 V to 46 V
- Half-step, full-step and microstepping mode
- Built-in protection diodes
- Internal PWM current control
- Low output saturation voltage
- Designed for unstabilized motor supply voltage
- Internal thermal shutdown

L6219 Datasheet pdf

bipolar stepper motor with current control

2009-01-10T18:41:00.000-08:00

The UDN2916B, UDN2916EB, and UDN2916LB motor drivers are
designed to drive both windings of a bipolar stepper motor or
bidirectionally control two dc motors. Both bridges are capable of
sustaining 45 V and include internal pulse-width modulation (PWM)
control of the output current to 750 mA. The outputs have been
optimized for a low output saturation voltage drop (less than 1.8 V
total source plus sink at 500 mA).

FEATURES
- 750 mA Continuous Output Current
- 45 V Output Sustaining Voltage
- Internal Clamp Diodes
- Internal PWM Current Control
- Low Output Saturation Voltage
- Internal Thermal Shutdown Circuitry
- Similar to Dual PBL3717, UC3770

UDN2916 Datasheet pdf

2A Step Motor Driver Circuit

2009-01-07T16:58:00.000-08:00

TWO PHASE BIPOLARSTEPPERMOTOR CONTROL CIRCUIT
This circuit drives bipolar stepper motors with winding currents
up to 2A.The diodes are fast 2A types.

L297
STEPPER MOTOR CONTROLLERS
The L297/A/D Stepper Motor Controller IC generates
four phase drive signals for two phase bipolar
and four phase unipolar step motors in microcomputer-
controlled applications. The motor can be
driven in half step, normal and wawe drive modes
and on-chip PWM chopper circuits permit switchmode
control of the current in the windings.

Feature
- NORMAL/WAWE DRIVE
- HALF/FULL STEP MODES
- CLOCKWISE/ANTICLOCKWISEDIRECTION
- SWITCHMODE LOAD CURRENT REGULATION
- PROGRAMMABLE LOAD CURRENT
- FEW EXTERNALCOMPONENTS
- RESET INPUT & HOME OUTPUT
- ENABLE INPUT

L297 Datasheet pdf

PWM Generator with Current Limit Circuit

2009-01-02T17:17:00.000-08:00

SG3524

The SG2524 and SG3524 incorporate all the
functions required in the construction of a
regulating power supply, inverter, or switching
regulator on a single chip. They also can be used
as the control element for high-power-output
applications. The SG2524 and SG3524 were
designed for switching regulators of either polarity,
transformer-coupled dc-to-dc converters, transformerless
voltage doublers, and polarity converter applications
employing fixed-frequency, pulse-width-modulation
(PWM) techniques. The complementary output allows
either single-ended or push-pull application. Each device
includes an on-chip regulator, error amplifier, programmable
oscillator, pulse-steering flip-flop, two uncommitted
pass transistors, a high-gain comparator, and current-limiting
and shut-down circuitry.

SG3524 Datasheet pdf

PWM Generator Circuit

PWM Generator Circuit

2008-12-27T00:00:00.000-08:00

PWM generator

Here is an assembly very simple to get an oscillator giving
a fixed frequency signal but variable duty cycle. It can - after
amplifier transistor - serve to control the rotation speed of a motor
with direct current or to adjust the power of a dew-heater. We use
once again a logic gate of a CD4093 circuit.

http://www.astrosurf.com/spectrohelio/schemelek-en.php

A Simple PWM Circuit Based on the 555 Timer

The 555 timer in the PWM circuit is configured as an astable
oscillator. This means that once power is applied, the 555 will
oscillate without any external trigger. Before the technical
explanation of the circuit, let's look at the 555 timer IC itself.

http://www.dprg.org/tutorials/2005-11a/index.html

Opamp PWM Generator Circuit

This uses the LM324, a 14-pin DIL IC containing four individual
op-amps and running off a single-rail power supply.
The sawtooth is generated with two of them (U1A and U1B),
configured as a Schmitt Trigger and Miller Integrator, and
a third (U1C) is used as a comparator to compare the sawtooth
with the reference voltage and switch the power transistor.

http://www.cpemma.co.uk/pwm.html

PWM Generator Circuit by Digital register method

an example circuit using the digital comparison method
when a microcontroller is available to set the 4-bit digital register
value. A write strobe is required from the micro to latch the 4 data
bits into the register. The 74HC161 counter is free-running,
the frequency being set by the 74HC14 oscillator section, where
it is roughly f = 1/(6.3RC). The resulting frequency of the PWM
signal will be 16 times less than this counter clock frequency,
since it requires 16 pulses to complete one "revolution" of the
counter. With R=2k and C=1nF this results in a counter
frequency of approximately 80kHz which will result in a PWM signal
frequency of 5kHz.

homepages.which.net/~paul.hills/Circuits/PwmGenerators

PWM using 555

IC1 astable gives a fixed square wave at pin 3, C1 and R1 derive
uS trigger pulses from IC1 and this will trigger IC2 monostable or
single shot, the voltage at pin 5 of IC2 will change the pulse width
output of IC2, to get it working all the three RC combinations
have to be figured out

schematics.blogspot.com/2004/10/pulse-width-modulation

HALF-BRIDGE MOSFET DRIVER CIRCUIT

2008-12-24T23:33:00.001-08:00

IN = PWM 0 to 95%
IR2111
The IR2111(S) is a high voltage, high speed power
MOSFET and IGBT driver with dependent high and
low side referenced output channels designed for halfbridge
applications. Proprietary HVIC and latch
immune CMOS technologies enable ruggedized
monolithic construction. Logic input is compatible with
standard CMOS outputs. The output drivers feature a
high pulse current buffer stage designed for minimum
driver cross-conduction. Internal deadtime is provided
to avoid shoot-through in the output half-bridge. The
floating channel can be used to drive an N-channel
power MOSFET or IGBT in the high side configuration
which operates up to 600 volts.

Features
- Floating channel designed for bootstrap operation
Fully operational to +600V
Tolerant to negative transient voltage
dV/dt immune
- Gate drive supply range from 10 to 20V
- Undervoltage lockout for both channels
- CMOS Schmitt-triggered inputs with pull-down
- Matched propagation delay for both channels
- Internally set deadtime
- High side output in phase with

IR2111 Datasheet pdf

High and Low Side Mosfet Driver Circuit

2008-12-21T04:14:00.000-08:00

IR2110
The IR2110/IR2113 are high voltage, high speed power MOSFET and
IGBT drivers with independent high and low side referenced output channels.
Proprietary HVIC and latch immune CMOS technologies enable
ruggedized monolithic construction. Logic inputs are compatible with
standard CMOS or LSTTL output, down to 3.3V logic. The output
drivers feature a high pulse current buffer stage designed for minimum
driver cross-conduction. Propagation delays are matched to simplify use in
high frequency applications. The floating channel can be used to drive an
N-channel power MOSFET or IGBT in the high side configuration
whichoperates up to 500 or 600 volts

Features
- Floating channel designed for bootstrap operation
Fully operational to +500V or +600V
Tolerant to negative transient voltage
dV/dt immune
- Gate drive supply range from 10 to 20V
- Undervoltage lockout for both channels
- 3.3V logic compatible
Separate logic supply range from 3.3V to 20V
Logic and power ground 5V offset
- CMOS Schmitt-triggered inputs with pull-down
- Cycle by cycle edge-triggered shutdown logic
- Matched propagation delay for

IR2110 Datasheet pdf

Power MOSFET Drivers Circuit

2008-11-23T00:25:00.000-08:00

1.5A Dual High-Speed Power MOSFET Drivers

The TC4426A/TC4427A/TC4428A are improved
versions of the earlier TC4426/TC4427/TC4428 family
of MOSFET drivers. In addition to matched rise and fall
times, the TC4426A/TC4427A/TC4428A devices have
matched leading and falling edge propagation delay
times.

Features:
- High Peak Output Current – 1.5A
- Wide Input Supply Voltage Operating Range: 4.5V to 18V
- High Capacitive Load Drive Capability – 1000 p in 25 ns (typ.)
- Short Delay Times – 30 ns (typ.)
- Matched Rise, Fall and Delay Times
- Low Supply Current:
- With Logic ‘1’ Input – 1 mA (typ.)
- With Logic ‘0’ Input – 100 μA (typ.)
- Low Output Impedance – 7Ω (typ.)
- Latch-Up Protected: Will Withstand 0.5A Reverse Current
- Input Will Withstand Negative Inputs Up to 5V
- ESD Protected – 4 kV
- Pin-compatible with TC426/TC427/TC428 and
TC4426/TC4427/TC4428
- Space-saving 8-Pin MSOP and 8-Pin 6x5 DFN Packages

TC4426 Datasheet pdf

Bidirectional Current Sensor

2008-06-21T23:02:00.000-07:00

Bidirectional Hall Effect Based Linear Current Sensor with
Voltage Isolation and 20 A Dynamic Range

ACS706ELC-20A
The Allegro ACS706 family of current sensors provides economical
And precise solutions for current sensing in industrial, automotive,
commercial, and communications systems. The device package allows
for easy implementation by the customer. Typical applications include
motor control, load detection and management, switched-mode power
supplies, and overcurrent fault protection.
Current Input Range Min -20 A Max 20 A
Output Voltage versus Current Input (Vcc = 5V)

Features
• Small footprint, low-profile SOIC8 package
• 1.5 mΩ internal conductor resistance
• Excellent replacement for sense resistors
• 1600 VRMS minimum isolation voltage between pins 1-4 and 5-8
• 4.5 to 5.5 V, single supply operation
• 50 kHz bandwidth
• 100 mV/A output sensitivity and 20 A dynamic range
• Output voltage proportional to ac and dc currents
• Factory-trimmed for accuracy
• Extremely stable output offset voltage
• Near-zero magnetic hysteresis
• Ratiometric output from supply voltage

ACS706ELC-20A Datasheet pdf

Overcurrent Protection Circuit

2008-06-17T04:42:00.000-07:00

Overcurrent Protection Circuit for High Side Relay Diver

LTC1154
The LTC1154 single high side gate driver allows using low
cost N-channel FETs for high side switching applications. An
internal charge pump boosts the gate drive voltage above
the positive rail, fully enhancing an N-channel MOS switch
with no external components. Micropower operation, with
8μA standby current and 85μA operating current, allows
use in virtually all systems with maximum effi ciency.
Included on chip is programmable overcurrent sensing.

A time delay can be added to prevent false triggering on
high inrush current loads.

Feature
- Fully Enhances N-Channel Power MOSFETs
- 8μA IQ Standby Current
- 85μA IQ ON Current
- No External Charge Pump Capacitors
- 4.5V to 18V Supply Range
- Short-Circuit Protection
- Thermal Shutdown via PTC Thermistor
- Status Output Indicates Shutdown
- Available in 8-Pin SOIC and PDIP Packages

LTC1154 datasheet pdf

Protected 2A Switch circuit

2008-06-08T00:00:00.000-07:00

Protected 2A Switch with Isolated Inputs , Fault Output circuit

LT1161
The LT1161 is a quad high-side gate driver allowing the
use of low cost N-channel power MOSFETs for high-side
switching applications. It has four independent switch
channels, each containing a completely self-contained
charge pump to fully enhance an N-channel MOSFET
switch with no external components.

Features

- Fully Enhances N-Channel MOSFET Switches
- 8V to 48V Power Supply Range
- Protected from –15V to 60V Supply Transients
- Individual Short-Circuit Protection
- Individual Automatic Restart Timers
- Programmable Current Limit, Delay Time, and
Auto-Restart Period
- Voltage-Limited Gate Drive
- Defaults to OFF State with Open Input
- Flowthrough Input to Output Pinout
- Available in 20-Lead DIP or SOL Package

LT1161 datasheet pdf

True RMS-to-DC IC

2008-01-06T00:51:00.000-08:00

MX536A and MX636
Maxim-IC
The MX536A and MX636 are true RMS-to-DC converters.
They feature low power and are designed to accept
low-level input signals from 0 to 7VRMS for the MX536A
and 0 to 200mVRMS for the MX636. Both devices accept
complex input waveforms containing AC and DC components.
They can be operated from either a single supply
or dual supplies. Both devices draw less than 1mA
of quiescent supply current, making them ideal for battery-
powered applications.

Feature
- True RMS-to-DC Conversion
- Computes RMS of AC and DC Signals
- Wide Response:
2MHz Bandwidth for VRMS > 1V (MX536A)
1MHz Bandwidth for VRMS > 100mV
- Auxiliary dB Output: 60dB Range (MX536A)
50dB Range (MX636)
- Single- or Dual-Supply Operation
- Low Power: 1.2mA typ (MX536A)
800μA typ (MX636)

Mx536,MX636 datasheet pdf

RMS to dc Circuit

2007-12-19T00:04:00.000-08:00

Circuit measures true-rms and average value
The circuit measures both the true-rms value and the
rectified average value of an ac signal.This design uses
two low-cost ICs
Operating from a single 5V supply, the circuit has an
input dynamic range of less than 30 mV to greater than 3V rms.

RMS-to-dc converter Circuit is accurate and stable
The circuit uses a low-cost analog multiplier, IC1; an
integrator, IC3A, R5, and C1; and an analog inverter, IC2, R3, R4,
and D1 to convert the analog VIN into a true-rms dc VOUT.
The input signal can be ac, dc, or a combination. With an
input-signal range of 0 to 2V, the circuit can handle ac signals
with crest factors up to 5

True RMS Detector Circuit
The op amp precision rectifier circuits have greatly eased
The problems of AC to DC conversion. It is possible to measure
millivolt AC signal with a DC meter with better than 1%
accuracy. Inaccuracy due to diode turn-on and nonlinearity is
eliminated, and precise rectification of low level signals isobtained

Extend RMS-To-DC Converter's Range
The AD736 rms-to-dc converter is a 1-V, full-scale device.
Voltage comparator IC3 can increase the full-scale input range to
10 V automatically. When the rms-to-dc operating range is exceeded
, the comparator's hysteresis switches in an attenuator at the
rms-to-dc converter's input. Concurrently, it adds a gain stage to
the circuit's output-buffer amplifier, maintaining a steady output
voltage.

True RMS-to-DC Converter

2007-12-12T04:15:00.000-08:00

AD736
Analog Devices, Inc.
The AD736 is a low power, precision, monolithic true rms-to-dc
converter. It is laser trimmed to provide a maximum error of
0.3 mV 0.3% of reading with sine wave inputs. Furthermore,
it maintains high accuracy while measuring a wide range of
input waveforms, including variable duty cycle pulses and triac
(phase) controlled sine waves.

Provides
200 mV full-scale input range (larger inputs with input attenuator)

High input impedance: 1012 Ω Low input bias current: 25 pA maximum

High accuracy: ±0.3 mV ± 0.3% of reading

RMS conversion with signal crest factors up to 5

Wide power supply range: +2.8 V, −3.2 V to ±16.5 V

Low power: 200 µA maximum supply current

Buffered voltage output

No external trims needed for specified accuracy

AD736 datasheet pdf

Application Note True RMS-to-DC Converter

RMS-to-DC converter circuit

2007-09-15T23:51:00.000-07:00

LTC1966
Precision Micropower,RMS-to-DC Converter

The LTC1966 is a true RMS-to-DC converter that utilizes
an innovative patented computational technique. The
internal delta-sigma circuitry of the LTC1966 makes it simpler
to use, more accurate, lower power and dramatically
more flexible than conventional log-antilog RMS-to-DC
converters.

LTC1966 datasheet pdf

Instrumentation Circuitry Using RMS-to-DC Converters

Measuring rms voltage

Phase Locked Loop IC

2007-08-05T03:28:00.000-07:00

LM565/LM565C Phase Locked Loop
General Description

The LM565 and LM565C are general purpose phase locked
loops containing a stable, highly linear voltage controlled oscillator
for low distortion FM demodulation, and a double balanced
phase detector with good carrier suppression. The
VCO frequency is set with an external resistor and capacitor,
and a tuning range of 10:1 can be obtained with the same
capacitor. The characteristics of the closed loop
system—bandwidth, response speed, capture and pull in
range—may be adjusted over a wide range with an external
resistor and capacitor. The loop may be broken between the
VCO and the phase detector for insertion of a digital frequency
divider to obtain frequency multiplication.

The LM565H is specified for operation over the −55°C to
+125°C military temperature range. The LM565CN is specified
for operation over the 0°C to +70°C temperature range.

LM565/LM565C Datasheet pdf

20-Bit ADC which digital filters

2007-05-05T06:53:00.000-07:00

CS5526
CS5526 are highly integrated A/D converters which include
An instrumentation amplifier, a PGA (programmable gain
amplifier), eight digital filters, and self and system calibration
circuitry.

The converters are designed to provide their own negative
supply which enables their on-chip instrumentation
amplifiers to measure bipolar ground-referenced signals
±100 mV. By directly supplying NBV with -2.5 V and
with VA+ at 5 V, 2.5 V signals (with respect to ground)
can be measured.

Features
lDelta-Sigma A/D Converter
- Linearity Error: 0.0015%FS
- Noise Free Resolution: 18-bits lBipolar/Unipolar
- 25 mV, 55 mV, 100 mV, 1 V, 2.5 V and 5 V
lChopper Stabilized Instrumentation Amplifier
lOn-Chip Charge Pump Drive Circuitry
l4-Bit Output Latch
lSimple three-wire serial interface
- SPI™ and Microwire™ Compatible
- Schmitt Trigger on Serial Clock (SCLK)
lProgrammable Output Word Rates
- 3.76 Hz to 202Hz (XIN = 32.768 kHz)
- 11.47 Hz to 616 Hz (XIN = 100 kHz)
lOutput Settles in One Conversion Cycle
lSimultaneous 50/60 Hz Noise Rejection
lSystem and Self-Calibration with
Read/Write Registers
lSingle +5 V Analog Supply
+3.0 V or +5 V Digital Supply
lLow Power Mode Consumption: 4 mW
- 1.8 mW in 1 V, 2.5 V, and 5 V Input Ranges

CS5526 datasheet pdf

Application note
Interfacing CS5526 to the 80C51
Interfacing CS5526 to the PIC16F84

2.5 V Voltage References IC

2007-02-06T02:34:00.000-08:00

MCP1525 2.5 V Voltage References IC

Description
The Microchip Technology Inc. MCP1525/41 devices
are 2.5V and 4.096V precision voltage references that
use a combination of an advanced CMOS circuit
design and EPROM trimming to provide an initial
tolerance of ±1% (max.) and temperature stability of
±50 ppm/°C (max.). In addition to a low quiescent
current of 100 μA (max.) at 25°C, these devices offer a
clear advantage over the traditional Zener techniques
in terms of stability across time and temperature. The
output voltage is 2.5V for the MCP1525 and 4.096V for
the MCP1541. These devices are offered in SOT-23-3
and TO-92 packages, and are specified over theindustrial
temperature range of -40°C to +85°C.

Features
• Precision Voltage Reference
• Output Voltages: 2.5V and 4.096V
• Initial Accuracy: ±1% (max.)
• Temperature Drift: ±50 ppm/°C (max.)
• Output Current Drive: ±2 mA
• Maximum Input Current: 100 μA @ +25°C (max.)
• Packages: TO-92 and SOT-23-3
• Industrial Temperature Range: -40°C to +85°C

MCP1525 Datasheet pdf

4-to-16 Decoder IC

2006-11-28T00:00:00.000-08:00

MM74HC154

New product of fairchild semoconductor
The MM74HC154 decoder utilizes advanced silicon-gate
CMOS technology, and is well suited to memory address
decoding or data routing applications. It possesses high
noise immunity, and low power consumption of CMOS with
speeds similar to low power Schottky TTL circuits.

The MM74HC154 have 4 binary select inputs (A, B, C, and
D). If the device is enabled these inputs determine which
one of the 16 normally HIGH outputs will go LOW. Two
active LOW enables (G1 and G2) are provided to ease
cascading of decoders with little or no external logic.

74HC154 datasheet pdf

12-Bit A/D Converter

2006-11-14T23:58:00.000-08:00

MCP3202
12-Bit A/D Converter with SPI® Serial Interface
The Microchip Technology Inc. MCP3202 is a successive
approximation 12-bit Analog-to-Digital (A/D) Converter
with on-board sample and hold circuitry. The
MCP3202 is programmable to provide a single
pseudo-differential input pair or dual single-ended
inputs.

FEATURES
• 12-bit resolution
• ±1 LSB max DNL
• ±1 LSB max INL (MCP3202-B)
• ±2 LSB max INL (MCP3202-C)
• Analog inputs programmable as single-ended or
pseudo-differential pairs
• On-chip sample and hold
• SPI® serial interface (modes 0,0 and 1,1)
• Single supply operation: 2.7V - 5.5V
• 100ksps max. sampling rate at VDD = 5V
• 50ksps max. sampling rate at VDD = 2.7V
• Low power CMOS technology
- 500nA typical standby current, 5μA max.
- 550μA max. active current at 5V
• Industrial temp range: -40°C to +85°C
• 8-pin PDIP SOIC and TSSOP packages

MCP3202 Datasheet pdf

SPI - Serial Peripheral Interface
The Serial Peripheral Interface (SPI) is used primarily for a
synchronous serial communication of host processor and
peripherals. However, a connection of two processors via SPI
is just as well possible and is described at the end of the chapter.

C Compiler Reference Manual
Example C program interface MCP3202 to microcontroller
MCP3208.C A/D converter functions

7-segment display circuit

2006-11-06T23:51:00.000-08:00

Circuit use SIPO ( CD4094 ) for control segment A to segment H
of 7-segment and use DECADE COUNTER ( CD4017 ) for scan
enable 7-segment (7- segment common cathode )

Timing chart of CD4017

4017 datasheet pdf

4094 datasheet pdf

Transient Suppressor Diode

2006-11-02T23:02:00.000-08:00

The overvoltage transient suppressor diode is designed for
Applications requiring a diode with reverse avalanche
characteristics for use as reverse power transient suppressor.

MR2835SK Transient Suppressor Diode datasheet

How To Select Transient Voltage Suppressors
There are important Transient Voltage Suppressor (TVS)
datasheet characteristics and ratings that require careful
comparisons to circuitcomponent limitations and
transientconditions before selecting the optimum component.

///////////////////////////////////////////////////////////////////////////////////
Transient Suppressor Diode Application

Application Note Of Transient Voltage Suppression
Transient Voltage Suppression (TVS) protection devices
such as shielded cables, crowbars, filters and clamping
devices have been widely used for a number of years to solve
EMI problems. These TVS devices can be used to achieve
higher EMI higher immunity levels without significantly
adding to the cost and complexity of the circuit.

Power Filter 12V Voltage Regulator Circuit
At input side of regulator, I inserted a series inductor in addition
to normal decoupling capacitor to form a LC filter, so that it can
resist transient voltage. If supply voltage temporary goes up,
it can be absorbed by regulator.

The application of relay coil suppression with DC relays
This application note has been written in response to the
Numerous application problems resulting from improper relay
coil suppression.

Thermistor

2006-10-30T03:56:00.000-08:00

1.What is thermistor ? and Thermocouple Characteristics

2. Thermistor for Inrush Current Limiter
Thinking Electronic Industrail Co., Ltd
Features
1. RoHS compliant
2. Body size Ф5mm~ Ф 30mm
3. Radial lead resin coated
4. High power rating
5. Wide resistance range
6. Cost effective
7. Operating temperature range
- 5mm :-40~+150℃
- 8~Φ10mm : -40~+170
- 13mm~Φ30mm : -40~+200
8. Agency Recognition: UL /cUL/TUV /CSA/CQC

Thermistor datasheet pdf

Thermistor Application
- Temperature measurement
- Temperature control
- Temperature compensation
- Inrush current suppressing
- Liquid level sensing

Thermistor Application Note pdf

Transient Voltage protection circuit

2006-10-23T03:21:00.000-07:00

The Effect of Non ideal Capacitors
- Characteristic of Capacitors
- The Effect of Non ideal Capacitors
- The Effect of ESL
- Insertion Loss Characteristics of Typical Two-terminal
Capacitors
- Typical ESL Values for Capacitors
- The Effect of Equivalent Series Resistance

Differential and Common Mode Noise
- Suppression circuit of differential mode noise
- Suppression circuit of common mode noise

- Noise Suppression by Common Mode Choke Coils
Common mode choke coils are used to suppress
common mode noise. This type of coil is produced by
winding the signal or supply wires one ferrite core.

Circuit Protection from Transient Voltage by Varistor
- Circuit Transient Voltage by Varistor
- Characteristic of Varistor

Varistor device datasheet
EPCOS varistor
Crimp style. Taping mode. Max. AC operating voltage.
Tolerance of varistor voltage. EPCOS metal oxide varistor.
Leaded Varistors. StandarD Series

EMC Filter Device

2006-10-11T07:54:00.000-07:00

EMC Filter Device
TGL Technology Co., Ltd.
Main Products: Manufacturers & Suppliers of EMI core,
EMC core, EMI Filter, EMI filters, EMI suppression, EMI
shielding

Belling Lee EMC Mains Filters
With the continuing development of electronics and its
applications into most areas of human activity it is important
to recognise the increasing danger of reducing the reliability
of equipment through electromagnetic interference.
Unplanned coupling of spurious signals into equipment can
cause inadvertent initiation of sequences leading to
unplanned events and happenings which can lead to
corruption of data, loss of revenue and danger to life.

GENERAL PURPOSE FILTERS
These general purpose filters provide adequate attenuation
for the suppression and protection of most machines,
and are available in current ratings up to 100 amps three
phase four lines.

EMI/EMC Suppression in Audio/Video Interfaces
All electronic products marketed worldwide undergo EMI/EMC
(electromagnetic interference/electromagnetic compatibility)
testing before they are offered for sale to prove that they will
not create interference, or be interfered with by other devices.
For testing purposes, products are grouped into two classes:
intentional radiators and unintentional radiators. For example,
cell phones and walkie-talkies intentionally radiate energy while
TVs, PCs, or laptops should not.

EMC Filters
Schaffner is uniquely able to offer the world's most compre
hensive ranges of EMC filters, RFI suppression chokes, line
conditioning and power quality products, feedthrough
components, pulse transformers and automotive solutions.
Products PCB Filters, IEC Inlet Filters, Single Phase Filters,
Three Phase Filters, Three Phase + Neutral Line Filters,
Open Frame Filters

Electronic Enclosures EMC shielding

2006-10-08T02:14:00.000-07:00

Use Shielded Electronic Enclosures To Meet
EMC Standards
Proper selection of shielding options early in the design cycle
ensures electromagnetic compatibility without sacrificing other
objectives.
Knowledge of shielding options and how to implement them
into initial product designs is vital to producing an electronic
packaging product that satisfies several important design
objectives. A properly applied shielding solution will meet
standards for electromagnetic compatibility (EMC), as well as
cost restrictions and the specific needs of high-power and
high-speed electronics.

Selecting magnetic shielding metals
High-permeability shielding material prevent interference from
driving sensitive circuits crazy

Shielding Strategies for Today's Electronic Enclosures
For as long as electronics have been around, enclosure engineers
have seen their role in the EMC design process as the clean-up
crew. Whatever design engineers could not solve with tricks of the
trade was left to them to handle. Unfortunately, this practice
continues, and an often-repeated process of trial and error to
contain electromagnetic interference shows up more often than
not in the testing phase.

Electronic Enclosures shielding
Effective EMI control prevents spurious signals from entering
or leaving an enclosure. Shields and filters are the predominant
techniques for controlling EMI.Shields can involve many
combinations of foils, conductive inks, paper, and adhesives.
For example, there are now shields that consist of silver ink
printed on 5-mil-thick polyester. After printing, a curing process
removes nonconductive solvents. The result is a homogeneous
shield that does not crack or delaminate when bent. The shield
can be mechanically fastened and grounded with solder tabs.
The cost is about the same as that for conventional laminated
designs.

Electronic Enclosures

2006-10-04T03:24:00.000-07:00

Bud Industries Quality electronic enclosures
Bud Industries is the United State's leading manufacturer of
standard electronic enclosures and custom electronic enclosures.

SERPAC ELECTRONIC ENCLOSURES
Top Manufacturer of Electronic Enclosures, Plastic Instrument
Cases, Project Boxes, and Enclosures

Electronic Enclosures
This enclosure consists of high-impact ABS (operating
temperature : -4°F to +212°F).The lid and the base equipped
with a tongue and groove
sealing system with a neoprene gasket. The mounting holes
and the lid-fixing screws are outside the seal, which prevents
moisture and dust from entering the enclosure. Internal
guide slots allow the vertical mounting of PCB assemblies.
Designed to meet IP65 of IEC529 and NAMA4 (dust- and
hose proof).
The bosses on the internal base allow the horizontal fixing
of PCBs or the connection of terminals, etc. with threaded
brass inserts.

ELBAG ELECTRONIC BOX
modular housing,Vertical rail mounting, Power Box , Cases
for potted circuit , housing with socket , custom housing ,
panel housing

Plastic Enclosures and Electrical Connector Enclosures
PacTec has designed and manufactured plastic electronic
enclosures since 1978. Search our extensive plastic enclosure
database to find the plastic boxes that will house your PCB.

Microcomputer Grounds in One- and Two-Layer PCB Design

2006-10-01T01:01:00.000-07:00

A microcomputer ground is a ground area on the bottom
layer underneath the microcomputer that becomes a ground
island for the noise made by the microcomputer.
This area should extend about 1/4 inch outside the outline
of the device and tie to the microprocessor ground. Ground
connections for the power-supply bypassing capacitors and
any bypassing capacitors on the pins also should tie to this
ground. Additionally, the ground area should extend out and
around the through holes for the oscillator leads, and the
bypass capacitors tied in to provide the smallest possible loop
area when viewed from the top.

The topside traces are shown in dotted line form on the bottom
side diagram for alignment purposes. Notice how the oscillator
capacitors lay back over the traces between the device and the
crystal. This eliminates loop area. The same is true for the
placement of the ferrite bead and Vcc bypass capacitor, being
centrally located with the main power lead running almost directly
under the lead finger for the ground.

PCB Design Guidelines For Reduced EMI
Texas Instruments

Isolate 4-20mA to Voltage Circuit

2006-09-26T08:42:00.000-07:00

The AD202 and AD204 are general purpose, two-port,
transformer-coupled isolation amplifiers that may be used in
a broad range of applications where input signals must be
measured, processed, and/or transmitted without a galvanic
connection.

AD202/AD204 application circuit

Picture shows an isolator receiver that translates a 4-20 mA
process current signal into a 0 V to 10 V output. A 1 V to 5 V
signal appears at the isolator’s output, and a –1 V reference
applied to output LO provides the necessary level shift
(in multichannel applications, the reference can be shared by
all channels). This technique is often useful for getting offset
with a follower-type output buffer.

The circuit as shown requires a source compliance of at least
5 V, but if necessary that can be reduced by using a lower value
of current-sampling resistor and configuring the input amplifier
for a small gain.

PCB Design Paper

2006-09-24T07:20:00.000-07:00

Calculation of PCB Track Impedance Paper (PDF)
The use of high-speed circuits requires PCB tracks to be
designed with controlled (characteristic, odd-mode, or
differential) impedances.
Wadell[1] is one of the most comprehensive sources of
equations for evaluating these
impedances.
This source includes many configurations including stripline,
surface microstrip, and their coplanar variants.

Current Carrying Capacity of Vias Paper (PDF)
We are frequently asked about the current carrying
capacity of vias.
To our knowledge, there have been no
studies of this particular topic, although we do know of
people who have useful insights into this issue.
What we offer here are some observations and a conceptual
framework for looking at the issue, with some resulting
guidelines that seem reasonable.

PCB Design Tutorial Paper (PDF)
You've designed your circuit, perhaps even bread boarded
a working prototype, and now it's time to turn it into a nice
Printed Circuit Board (PCB) design. For some designers,
the PCB design will be a natural and easy extension of the
design process. But for many others the process of designing
and laying out a PCB can be a very daunting task.

PCB Clearances Table

2006-09-19T01:36:00.000-07:00

For non-mains voltages, the IPC standard has a set of tables
that define the clearance required for various voltages.
A simplified table is shown here. The clearance will vary depending
on whether the tracks are on an internal layers or the external
surface. They also vary with the operational height of the board
above sea level, due to the thinning of the atmosphere at high
altitudes.
PCB Clearances for Electrical Conductors Table
Voltage (DC or Peak AC) - Internal - External (<3050m)
- External (>3050m)
0-15V - 0.05mm - 0.1mm - 0.1mm
16-30V - 0.05mm - 0.1mm - 0.1mm
31-50V - 0.1mm - 0.6mm - 0.6mm
51-100V - 0.1mm - 0.6mm - 1.5mm
101-150V - 0.2mm - 0.6mm - 3.2mm
151-170V - 0.2mm - 1.25mm - 3.2mm
171-250V - 0.2mm - 1.25mm - 6.4mm
251-300V - 0.2mm - 1.25mm - 12.5mm
301-500V - 0.25mm - 2.5mm - 12.5mm

PCB Design Tutorial by David L. Jones

Track Width Reference Table

2006-09-17T22:50:00.000-07:00

Track Width Reference Table (for 10deg C temp rise).
Track Width is in Thous (mils)
Current (Amps) - Width for 1oz - Width for 2 oz - milli Ohms/Inch
1 - 10 - 5 - 52
2 - 30 - 15 - 17.2
3 - 50 - 25 - 10.3
4 - 80 - 40 - 6.4
5 - 110 - 55 - 4.7
6 - 150 - 75 - 3.4
7 - 180 - 90 - 2.9
8 - 220 - 110 - 2.3
9 - 260 - 130 - 2.0
10 - 300 - 150 - 1.7

As a start, you may like to use say 25 thou for signal tracks, 50 thou for power
and ground tracks, and 10-15 thou for going between IC and component pads.
Some designers though like the “look” of smaller signal tracks like 10 or 15 thou,
while others like all of their tracks to be big and “chunky”. Good design practice
is to keep tracks as big as possible, and then to change to a thinner track only
when required to meet clearance requirements.

The thickness of the copper on the PCB is nominally specified in ounces per
square foot, with 1oz copper being the most common. You can order other
thicknesses like 0.5oz, 2oz and 4oz. The thicker copper layers are useful for high
current, high reliability designs.

PCB Design Tutorial by David L. Jones

PCB Track Width Calculator
PCB Track Width Calculator
This page calculates approximations to the
ANSI/IPC-D-275 and IPC-2221 design standards for PCB trace width. www.desmith.com/NMdS/Electronics/TraceWidth.html

The PCB Track Width Calculator
The PCB Company - Supplier of Printed Circuit Boards.
www.pcbco.com.au/tracecalc.html

PCB Trace Width Calculator
QUESTION: Very cool PCB width tool! I would like to know its limits though.
I entered a 65 amp current requirement and it returned a track width that must
www.geocities.com/capecanaveral/lab/9643/TraceWidth.htm

Bar Graph Display

2006-09-13T09:10:00.000-07:00

LTA-1000G is a ten rectangular bar graph display where a
continuously large bright source of light is required This device
utilizes green led chip

Voltage to Bar Graph Circuit

2006-09-11T22:14:00.000-07:00

if you want to create circuit for display 10-step voltage divider.
This device is easy way for make voltage to bar graph circuit

LM3914 Dot/Bar Display Driver
The LM3914 is a monolithic integrated circuit that senses
analog voltage levels and drives 10 LEDs, providing a linear
analog display. (voltage to bar graph circuit )

Features
- Drives LEDs, LCDs or vacuum fluorescents
- Bar or dot display mode externally selectable
- Expandable to displays of 100 steps
- Internal voltage reference from 1.2V to 12V
- Operates with single supply of less than
- Inputs operate down to ground
- Output current programmable from 2 mA
- No multiplex switching or interaction between
- Input withstands ±35V without damage or
- LED driver outputs are current regulated, open-collectors
- Outputs can interface with TTL or CMOS
- The internal 10-step divider is floating and referenced to a
wide range of voltages

Precision Voltage-to-Current Converter Circuit

2006-09-10T03:34:00.000-07:00

The AD620, along with another op-amp and two resistors, makes
a precision current source circuit.

The op-amp buffers the reference terminal to maintain good CMR.
The output voltage, VX, of the AD620 appears across R1, which
converts it to a current. This current, less only the input bias current
of the op amp, then flows out to the load.
where
Vx = [(Vin+) – (Vin-)] * G
IL = Vx / R1
Circuit operates on 1.8 mA, ±3 V

Gain(G) is resistor-programmed by Rg
Rg = 49.4K ohm / (G-1)

Maximum power of a two terminal device

2006-09-06T05:56:00.000-07:00

The input impedance of a two terminal device may be show in
Picture below. The internal resistance Ri were connected in series
With the internal voltage source E. The connecting terminals as A
And B, and the open circuit voltage presented at these terminals is
E

if an external load R in connected to the device , the voltage
Presented at the output terminals will be dependent on the value of
R. The potential presented at the output terminals is

Eab = E*R/(R + Ri)

The power is given by

P = Eab/R =[ [E*R/(R + Ri)]^2] / R

And the maximizing condition

dP/dR = 0

is applied. There results

R = Ri

Isolated Thermocouple Transducer Circuit

2006-09-05T05:42:00.000-07:00

The AD202 are general purpose, two-port, transformer-
coupled isolation amplifiers

In applications where the output of thermocouples must be
isolated, a low drift input amplifier can be used with an
AD204,as shown in Picture.

A three-pole active filter is included in the design to
get normal-mode rejection of frequencies above a few Hz
and to provide enhanced common-mode rejection at 60 Hz.
If offset adjustment is needed, it is best done at the trim pins
of the OP07 itself; gain adjustment can be done at the
feedback resistor.
Note that the isolated supply current is large enough to
Mandate the use of 1 mF supply bypass capacitors.

This circuit from AD202 Application

Programmable Gain Thermocouple Amplifier Circuit

2006-09-04T00:39:00.000-07:00

AD624 is Instrumentation amplifier of Analog Devices,
designed primarily for use with low level transducers,including
load cells, strain gauges, thermocouple and pressure transducers.

Picture shows the AD624 being used as a software programmable
gain amplifier. Gain switching can be accomplished with
mechanical switches such as DIP switches or reed relays. It
should be noted that the “on” resistance of the switch in series
with the internal gain resistor becomes part of the gain equation
and will have an effect on gain accuracy.

A significant advantage in using the internal gain resistors in a
programmable gain configuration is the minimization of thermocouple
signals which are often present in multiplexed data
acquisition systems.
If the full performance of the AD624 is to be achieved, the user
must be extremely careful in designing and laying out his circuit
to minimize the remaining thermocouple signals.

Interfacing Pressure Transducer Circuit

2006-09-03T00:53:00.000-07:00

AD620 useful in many bridge applications
the AD620 is especially suitable for higher resistance pressure
Transducer powered at lower voltages where small size and low
Power become more significant.

Picture shows a 3 kΩ pressure transducer bridge powered from 5 V.
In such a circuit, the bridge consumes only 1.7 mA. Adding the
AD620 and a buffered voltage divider allows the signal to be
conditioned for only 3.8 mA of total supply current. Small size and
low cost make the AD620 especially attractive for voltage output
pressure transducers.

Since it delivers low noise and drift, it will also serve applications

such as diagnostic noninvasive blood pressure measurement.

AD620 datasheet pdf

Selecting a Transducer

2006-09-02T02:55:00.000-07:00

Selection of the appropriate transducer is therefore the first and most
importance step in obtaining accurate results. The equations should be
asked before a transducer can be select
- What is the physical quantity to be measured ?
For determining the type and range of the measureand.
- Which transducer principle can best be used to measure this quantity?
For determining the input and output characteristic of the
transducer be compatible with the recording or measurement system.
- What accuracy is required for this measurement?
The accuracy requirement of the total system determine the
degree to which individual factor contributing to accuracy must be
considered. Some of these factors are
1. basic electronic and mechanical characteristic of the transducer
- Type and range of measurand
- Sensitivity
- Excitation
- Mechanical and electrical connection
- Mounting provisions
- Corrosion resistance
2. Transducer accuracy , as an independent component
- Nonlinearity effect
- Hysteresis effect
- Frequency response
- Resolution
3. Transducer’s compatibility
- Zero balance provisions
- Sensitivity tolerance
- Impedance matching
- Insulation resistance

Inductance Transducer Type

2006-08-24T23:15:00.000-07:00

Passive Transducers is require external power
- Magnetic circuit transducer
operation = self inductance or mutual inductance of ac-excited coil is
varied by change in the magnetic circuit
- Reluctance pickup
operation = reluctance of the magnetic circuit is varied by change the
position of the iron core of a coil
- Differential Transformer
operation = the differnential voltage of two secondary winding of a
transformer is varied by positioning the magnetic core through an
external applied force
- Eddy current gage
operation = Inductance of a coil is varied by the proximity of an eddy
current plate
- Magnetostriction gage
operation = Magnetic properties are varied by pressure and stress

Capacitance Transducer Type

2006-08-24T02:18:00.000-07:00

Passive Transducers is require external power
- variable capacitance pressure gage
operation = distance between two parallel plates is varies by an external
applied force
- capacitor microphone
operation = sound pressure varies the capacitance between a fix plate and
a movable diaphragm
- dielectric gage
operation = variation in capacitance by changes in the dielectric

Transducer Type

2006-08-23T03:34:00.000-07:00

Passive Transducers is require external power,producing a variation in
Some electrical parameter which can be measured as a voltage or
current variation.

Resistance Transducer Type
- potentionmetric
operation = position of slider by external force varies the resistance in a
potentiometer or bridge circuit
- resistance strain gage
operation = resistance of a wire or semiconductor is change by compression
due to external appile stress
- pirani gage
operation = resistance of a heating element is varied by convection colling of
gas
- thermometer
operation = resistance of pure metal wire with a large positive temperature
coefficient of resistance varies with temperature.
- thermistor
operation = resistance of certain metal oxides with negative temperature
coefficient of resistance varies with temperature.
- hygrometer
operation = resistance of a conductive strip change with moisture content
- photoconductive cell
operation = resistance of the cell as a circuit element varies with incident

Constant current source circuit

2006-08-18T23:34:00.000-07:00

We can use a voltage reference turn into a Constant current source
circuit and use pnp-transistors for current-boosting

By op amp action ,the voltage across R is away Vref , give
Ie = Vref / R

Ie = Ib + Ic = (Ic/B) + Ic

Ic = [B/(B+1)] *Ie

Io = Ic = [B/(B+1)] * Vref / R about Vref / R
VL = Io*RL
Where maximum voltage of Vl(max) <>

We can adjust output current by adjust current setting resistance R

Extend current lm78xx regulator circuit

2006-08-16T20:39:00.000-07:00

LM340/LM78XX Series
3-Terminal Positive Regulators
The LM140/LM340A/LM340/LM78XXC monolithic
3-terminal positive voltage regulators employ internal
current-limiting, thermal shutdown and safe-area compensation,
making them essentially indestructible. If adequate heat
sinking is provided, they can deliver over 1.0A output current.
They are intended as fixed voltage regulators in a wide
range of applications including local (on-card) regulation for
elimination of noise and distribution problems associated
with single-point regulation. In addition to use as fixed voltage
regulators, these devices can be used with external
components to obtain adjustable output voltages and currents.

Applications circuit of LM340/LM78XX Series
where
Io = Iq + Ireg
Iq = B *Ib
Ib = Ireg – Vbe/R1

Iq = B(Ireg – Vbe/R1)
Io = B*Ireg – B*Vbe/R1 + Ireg
Io = (B+1)*Ireg – B*Vbe/R1
R1*Io = R1 (B+1)*Ireg – B*Vbe

B*Vbe = R1[(B+1)*Ireg - Io]

R1 = B*Vbe / [(B+1)*Ireg - Io]

Example
We want to make regolater circuit 3 A
We choose current of regulater 0.6 A for safety
2N6133 for Q1
Io = 3A
Ireg = 0.6 A
Vbe = 1.4 V
B = 20

R1 = 20*1.4/[(20+1)*0.5 – 3]
R1 = 2.91

We choose R1 = 3 ohm

Half-wave precision rectifiers circuit

2006-08-15T19:47:00.000-07:00

A half-wave rectifier is a circuit that passes only the positive or only the negative
Portion of a wave ,while blocking out the other portion
Rectifiers are impremented using diodes. The nonzero forward-voltage drop of
A pactical diode may cause intolerable errors in low-level signal

Proceeding of half-wave precision rectifiers circuit we separate are two case
Case 1 Vi > 0 negative input of op amp is higher positive input ,the op amp
Output = 0 ,I1 will flow through R1 and D1 ,hence Vo = 0

Case 2 Vi <>
Output = 1 ,I2 will flow through R2,R1 and D2 ,but the voltage at positive input
Must equal the voltage at negative input ,hence I2 = (0-Vi)/R1 = (Vo-0)/R2
This gives Vo = (-R2/R2)Vi

Circuit behavior
Vo = 0 for Vi > 0
Vo = -(R2/R1)Vi for Vi <>
Example waveform

Input Offset Voltage Null Circuit

2006-08-14T02:03:00.000-07:00

This circuit is application of OP07. adjust variable resistor for null Offset
Voltage output at initrial state

Op07
Op07 represent a breakthrough in operational amplifier performance.
Low offset and long-term stability are achieved by means of a low-noise,
chopperless, bipolar-input-transistor amplifier circuit. For most applications,

external components are not required for offset nulling and
frequency compensation. The true differential input, with a wide input
voltage range and outstanding common-mode rejection, provides
maximum flexibility and performance in high-noise environments and in
noninverting applications. Low bias currents and extremely high input
impedances are maintained over the entire temperature range.
The OP07 is unsurpassed for low-noise, high-accuracy amplification of
very low-level signals.

Simple Large Fan-In AND Gate circuit

2006-08-13T09:16:00.000-07:00

We can make simple Large Fan-In AND Gate circuit by one Voltage
Comparators from circuit below

Vout = A and B and C and D and ….

This circuit is application of LM139
LM139
Low Power Low Offset Voltage Quad Comparators
The LM139 series consists of four independent precision
voltage comparators with an offset voltage specification as
low as 2 mV max for all four comparators. These were
designed specifically to operate from a single power supply
over a wide range of voltages.

All pins of any unused comparators should be tied to the
negative supply.

The output of the LM139 series is the uncommitted collector
of a grounded-emitter NPN output transistor. Many collectors
can be tied together to provide an output OR’ing function.

Vo = A or B or C

On-Off Control With Hysteresis Circuit

2006-08-10T00:59:00.000-07:00

We can use inverting Schmitt trigger circuit for this application
Inverting Schmitt trigger
the circuit can be view as an inverting –type threshold detector whose
threshold is controlled by the out put since the output has two stable
state, this threshold has two possible values,namly

Vth = R1*Voh/(R1+R2)
Vtl = R1*Vol/(R1+R2)

The hysteresis width is defined as
Hw = Vth – Vtl = R1*( Voh – Vol )/( R1 + R2 )

Behaviour of circuit show in below picture.

Sample waveforms