PhotoMOSFET Application and Markets

Optocoupler - what is it for?

Perfect fit for an electronic device to transfer a communication signal between two circuits:

• Galvanically isolates low-voltage devices from high-voltage circuits
• Protects the useful signal from electrical noise (circuit surges, noise coupling)
• Protects sensitive control circuitry or people from high voltages
• Low voltage digital signals can control larger voltages

Optocouplers provides a protection of a safe circuit from a potentially hazardous circuit or unwanted noise.

Optocoupler versus PhotoMOSFET

MOSFET – Metal Oxide Field Effect Transistor

• Switch-like transistor
• Three terminals Drain (D), Source (S), Gate (G) + Body
• Operated by a voltage attached to the Gate
• No galvanic isolation between input and output

PhotoMOSFET – Optocoupler + CMOS

• Symmetrical pair of p-type and n-type MOSFETs
• Gate is operated by photocurrent from infra LED
• Galvanic Isolation and bidirectional function achieved

Introduction to PhotoMOSFET Relays

What is a Photo MOSFET Relay?

• Control Side: Infra LED
• Output Side: PVG & MOSFET output

Functionality

• Current flow through IR LED generates IR frequency light
• IR incident on PVG, (photovoltaic generator), photo diode array creates photo current & generates voltage 
• MOSFET Gate turns on when voltage exceeds threshold level

Features / Advantages / Disadvantages

Advantages vs. Reed Relay

• Longer life expectancy
• Fast switching speed
• Smaller package
• No bounce of contacts

Features

• AC or DC switching in small package
• Fast switching, no contact bounce, low noise
• Long life and reliability
• High peak load currents 3 to 6 Amps (47 and 36 series)
• Impervious to dirty environments, shock/vibration proof
• AEC-Q101 Automotive (47, 38, 40 series)
• Control low-level analog signals to high-level loads: (LED’s, relays, lamps, solenoids)
• Stable on resistance

Disadvantages vs. Reed Relay

• Isolation voltage across contacts
• Higher contact resistance
• Higher Leakage currents
• Temperature dependent
• ESD sensitive

Applications and Markets

Measurement Equipment 

• Memory Testers, Logic Testers, Board Testers, Data Loggers, Multi-point Recorders, Flow meters, Timers

BMS

• Battery monitoring, Battery Balancing, Isolation testing

Telecommunication Equipment

• Modems, Electronic switching systems, PBX, multi-function telephones, Fax

Industrial Equipment 

• Robotics, Process Controllers, PLC, Compressors, Numerical Controllers, Thermostats, Relay output I/O boards, actuator drivers

Medical Equipment

• Electrocardiograph, Electroencephalograph, X-ray CT scanners

Security Equipment 

• Home, Office & Building security systems

Home Electronic Equipment 

• Air conditioners, Refrigerators, Microwave ovens, Washing machines, Internet TV, Home Network Box

Telemetry Equipment

• Automatic meter reading systems, Home medical equipment, Plant monitoring systems, Security systems

• Share: