Opto Electronics DevicesAnd Their ApplicationsIn Power Electronics

Presented by Khoi TranApplication Engineer

Fairchild Semiconductor

Agenda

• What are Optocouplers ?• Where are they used ?• What are their Characteristics?

What are Optocoupler?

• An optocoupler consists of a light source and a photosensitive detector

• The light source is an infrared LED that is used to convert current to light.

• The photosensitive detector is a silicon photodiode which converts the light back to current.

The Phototransistor Optocoupler

• Elements• LED Source• Package• Phototransistor 3

5

6

7

8

2

4

1

Co-planar Construction

Double Molded Construction

What are the KEY Characteristics ?

• Collector Base Current Transfer ratio• CTRcb = Icb/IF

• Transistor Current Gain• HFE = Ice / Icb

• Current Transfer Ratio - CTRce•CTRce = Ice/IF•CTRce = CTRcb * HFE

Ice vs. IF

CTRcb vs LED Current

Saturated Ice vs LED Current

Icb vs IF

Non Saturated CTR vs LED Current

Saturated CTR vs Collector Current

Non Saturated CTR vs Collector Current

HFE vs Base Current , Ib

HFE vs Collector Current

Turn-OFF Time

Why are they Used?

• To Protects Against :– Electromagnetic Interference– High tension power lines– Noise conducted through the power

lines– Electrostatic Discharge, Lightning – Digital Data Crosstalk

• To Communicate Digital Data – Compatible with Logic Family or Load

KEY Characteristics of the Isolator

• Electro-mechanical – Relay – Switch

• Electro-Optical– Optical Fiber– Emitter to Detector– Optocoupler

• Capacitive– Single ended– Differential

• Electro-Magnetic– Magneto resistive– Hall Effect– Transformer

Acoustic Surface wavesTransducer - Receiver

Radio FrequencyRemote controlMicrowave

Optocouplers Solve the NOISE Problem

“Systems” & “Approvals”

• Couplers must fulfill• Safety Standards:

• Fairchild Couplers are • classified in “Systems”. • A System represents the• same Technology, Material

e.t.c.• and is indicated with a Capital

• The System is the Indicator• for Approvals

Approvals forSafety Requirements:Double Protection &Reinforced Insulation

Where are they used ?

• Applications

• Industrial Control

• Power Supply

• Telecommunications

• Instrumentation

Insulation and Isolation in a Switch Mode

Power Supply

SwitchingControl Circuit

Optical Coupled Precision Voltage

Reference

Feedback Amplifier FOD2741 Composition

• The FOD2741/2 consists of adjustable precision zener diode and a phototransistor optocoupler. Typical

• Current gain , CTR, is 60% for an IF = 1mA, and Vce = 0.5V. • The device offers a 2.5V +- 1% bandgap reference, a 60dB (OLG)

1 MHz(BWP) differential amplifier

Vin

FOD2741

Comp

LED

Vref

Comp

Vin

Vref

Comp

Vin

DC Isolation Amplifier

Error Amplifier

Feedback Amplifier Interconnection

• Values of resistors and capacitors are used in the demo board supporting the KA5M0365

FOD2741

R6 680 R3

470

R4

,3K

C2

,.1

uF

C1 .033uF

R2 3.3K

R5, 1K

R1,1K

4 uA 0.9 mA

2.5R

R

+

–Vfb

5V 12V0.5V

Voffset

2.5V

KA5M0365

Industrial Control

InterfaceSensors

Temperature FlowLevel

Motion SystemsPumpsMixersValves

CommunicationsLocalRemote

ApplicationsProcess Controller - Interfaces

• Interfaces– Data– Motion– Sensor– Valves &

Actuators

Controller InputI / O

Interface Board

SignalConditioning

Multiplexer

Level DetectorLogic Interface

SignalConditioning

Isolation Barrier

1 - 4

5 - 8 Level DetectorLogic Interface

ILQ620

ILQ620

ToµController

SFH6700

Process Control I/O: AC/DC Signal Measurement

• Parallel A / D

DataA / D

Converter

Control

16

Isolation

CNY17

ILQ621

ILQ621

Barrier

SignalConditioning

1

DC / DC Converter

Process Control I/O: AC/DC Signal Measurement

• AC / DC Measurement Card

Signal Conditioning

Signal Conditioning

IsolationBarrier

DataOut

Control

DC/DCConverter

µController

SAB80C5XXSAB80C16X

Seria

l I/O

MU

X A

/D

Converte

rSFH6700

SFH6700

1

16

ApplicationsIndustrial Data

Communications• Isolate and •

Communicate– Device Net– CAN BUS– PROFI BUS– Genius Bus– Fieldbus– Modbus– 10Base-T– RS - 232– RS - 422– RS - 485

ApplicationMotion Control

Motor ControlHigh Speed CouplersTRIAC Drivers

Sensor FeedbackHigh Speed Couplers

Process Controller - Outputs

Boards or Module

Loads

LogicSFH67XX

Analog 4-20 mA

High Power DCSFH6345

TRIAC

AC Switch—SSR

IL410

MOSFET BUZ XX

AC / DC Switch

IL300

Con

troll

er

LH1485

IGBT—BUP XX

Motors, relays, solenoids

Large motors

Digital interfaces

Sensor feedback

Motors, relays,solenoids, lamps, heaters

Can I determine the Switching

Characteristics of a Phototransistor ?

• YES…– By using a SPICE Simulation

– By Modeling the LED to Phototransistor• GAIN & Timing performance

– By Modeling the Transistor Gain • and Its Charge Storage Characteristics

Phototransistor SPICE Model

D1 LED

VM

Current to Voltage Converter

6

2

Collector

Voltage to Current Converter

5Base

1

4Emitter

C1,200pF

R1, 250ž

H1G1

MOC207 PhototransistorSPICE Model

• .SUBCKT OPMOC207 1 2 5 6 7

• *ANODE INPUT=1, CATHODE = 2; EMITTER OUTPUT=5

• +;COLLECTOR OUTPUT=6; base input=6• VM 1 12 DC 0• D1 12 2 LED• R1 10 11 250• C1 11 0 200PF• H1 10 0 VM 2.7E-3• G1 5 7 11 0 1.0• Q1 6 7 5 QNPN• .MODEL LED D(IS=25E-13 RS=.55 CJO=35P

N=2.0)• .MODEL QNPN NPN(IS=3.33E-11 NF=1.35 CJC=12P

CJE=35P TF=1.0N • + TR=500N BF=778 BR=10 IKF=.1 VAF=100)• .ENDS OPMOC207

MOC207 PhototransistorSPICE Program

• X1 1 0 0 3 9 OPMOC207• IIN 0 1 DC .001 AC .1 PULSE 0

• +10E-3 100NS 100NS 100NS 10US 40US• RL 7 3 1000• VCC 7 0 5• RB 9 0 100e3

• .DC IIN 0 .01 .0005• .PLOT DC V(3) I(VCC)• .PRINT DC V(3) V(1) I(VCC)• .TRAN 25NS 40US• .PRINT TRAN V(3) I(IIN)• .PLOT TRAN V(3) I(IIN)• .OP• .END

MOC207 Phototransistor Interface Schematic

CTRcb = 0.0027 HFE = 788

Rb, 100K

RL,1K

R2

GND1

Output3

5

6

7

8MOC207

2

4

1

Vcc

GND2

I(IIN)