opto couplers types and its applications

Opto Couplers Types And Its Applications

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Introduction:

A lot of electronic equipment nowadays is using opt coupler in the circuit. An opt coupler or sometimes refer to as opt isolator allows two circuits to exchange signals yet remain electrically isolated. This is usually accomplished by using light to relay the signal. The standard opt coupler circuits design uses a LED shining on a phototransistor-usually it is a NPN transistor and not PNP. The signal is applied to the LED, which then shines on the transistor in the IC.

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What is Opto-Isolators or Opto-Couplers

Opto-isolators or Opto-couplers, are made up of a light emitting device, and a light sensitive device, all wrapped up in one package, but with no electrical connection between the two, just a beam of light. The light emitter is nearly always an LED. The light sensitive device may be a photodiode, phototransistor, or more esoteric devices such as thyristors, TRIACs etc.







Opto Couplers Module

SCR, photodiodes.

TRIAC of other semiconductor switch as an output

Incandescent lamps.

Neon bulbs or other light source.







Opto−Diacs

The Opto-Diacs are available in form of ICs and can be implemented using a simple circuitry.

Simply provide a small pulse at the right time to the Light Emitting Diode in the package.

The light produced by the LED activates the light sensitive properties of the diac and the power is switched on.

The isolation between the low power and high power circuits in these optically connected devices is typically several thousand volts.







Opto-Diacs Pin Description







4 Different Opto Couplers Available

1. MOC3020

2. MOC3021

3. MCT2E

4. MOC363







MOC3020

MOC3020 Opto Couplers comes in 6-pin DIP







Working Principle of MOC3020

The MOC3020 are designed for interfacing between electronic controls and power triac.

It is used to control resistive and inductive loads for Vac operations.

The principle used in Opto-coupler is, MOC’s.

It is promptly available in integrated circuit form.







Working Principle of MOC3020

To work the circuit give a small pulse at the right time to the LED in the package.

The light produced by the LED activates the light sensitive properties of the diac and the power is switched on.

The isolation between the low power and high power circuits in these optically connected devices is typically few thousand volts.







Features of MOC3020 400 V Photo-TRIAC Driver Output.

Gallium-Arsenide-Diode infrared source and optically-coupled silicon triac driver.

High isolation – 500 Vpeak.

Output driver designed for 220 Vac.

Standard 6-terminal plastic DIP.

Directly interchangeable with Motorola MOC3020, MOC3021 and MOC3022.







Typical applications of MOC3020

Solenoid/valve controls

Lamp ballasts

Interfacing microprocessors to 115/240 Vac peripherals

Motor controls

Incandescent lamp dimmers







MOC3021 MOC3021 is an opto-coupler designed for triggering

TRIACS. By using this we can trigger anywhere in the cycle, so can call them as non-zero opto-coupler. MOC3021 are very widely used and can be quite easily obtained from many sources. It comes in 6-pin DIP







Pin Description MOC3021

Pin 1: Anode

Pin 2: Cathode

Pin 3: No connection (NC)

Pin 4: Main terminal









Features

400 V Photo-triac driver output.

Gallium-Arsenide-Diode Infrared Source and Optically-Coupled Silicon triac driver.

High Isolation 7500 V Peak.

Output Driver Designed for 220 Vac.

Standard 6-terminal plastic DIP







Applications of MOC3021


Lamp ballasts

Interfacing microprocessors to 115/240 Vac peripherals

Motor controls

Incandescent lamp dimmers







MCT2E

The MCT2E series of opto-coupler devices each consist of gallium arsenide infrared LED and a silicon NPN phototransistor. They are packaged in a 6-pin DIP package and available in wide-lead spacing.







MCT2E Pin Description

Pin 1: Anode.

Pin 2: Cathode.

Pin 3: No connection.

Pin 4: Emitter.

Pin 5: Collector.

Pin 6: Base.







MCT2E Features

Isolation test voltage 5000 VRMS

Interfaces with common logic families

Input-output coupling capacitance < 0.5 pF

Industry standard dual-in-line 6 pin package

Compliant to RoHS directive 2002/95/EC

The opto-coupler usually found in switch mode power supply circuit, read relay driving, industrial controls, digital logic inputs and in many electronic equipments







Application of MCT2E

It is a combination of 1 LED and a transistor. Pin 6 of transistor is not generally used and when light falls on the base-emitter junction then it switches and pin5 goes to zero.

When logic zero is given as input then the light doesn’t fall on transistor so it doesn’t conduct which gives logic one as output.

When logic 1 is given as input then light falls on transistor so that it conducts, that makes transistor switched ON and it forms short circuit this makes the output is logic zero as collector of transistor is connected to ground.

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MOC363

The MOC3063 devices consist of gallium arsenide infrared emitting diodes optically coupled to monolithic silicon detectors performing the functions of zero voltage crossing bilateral triac drivers. It is also a 6-pin DIP.







MOC363 Pin Description

Pin 1: Anode

Pin 2: Cathode











MOC363 Features

Simplifies logic control of 115/240 Vac power

Zero crossing voltage

dv/dt of 1500 V/µs typical, 600 V/µs guaranteed

VDE recognized

Underwriters Laboratories (UL) recognized







MOC363 Applications


Static power switches

Temperature controls

AC motor starters and drivers

Lighting controls

E.M. contactors

Solid state relay







Working of MOC3063

From the circuit, we have an opto-coupler MOC3063 with an LED SCR type combination.







Working of MOC3063

Additionally while using this Opto-coupler with microcontroller and one LED can be connected in series with MOC3063 LED to indicate when high is given from micro controller such that we can know that current is flowing in internal LED of the Opto-coupler. When logic high is given then the current flows through LED from pin 1 to 2.

The LED light falls on SCR causing 6 and 4 to close only at the zero cross of the supply voltage. During each half cycle current flows through SCR gate, external series resistor and through SCR for the main thyristor/triac to trigger for the load at the beginning of the supply cycle always to operate.







The opto coupler usually found in switch mode power supply circuit in many electronic equipment. It is connected in between the primary and secondary section of power supplies. The opto-coupler application or function in the circuit is to:

Monitor high voltage.

Output voltage sampling for regulation.

System control micro for power ON/OFF.

Ground isolation.

Application Of Opto Couplers

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Most commonly used is an opto-coupler MOC3021 an LED diac type combination. This IC is interfaced with a microcontroller and an LED is connected in series to the IC, which glows to indicate a logic High pulse from the microcontroller so that we can know that current is flowing in internal LED of the opto-IC.

Conclusion





opto couplers types and its applications

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