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PhotoMOSFET Application and Markets

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 - what is it for.png

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

Optocoupler versus PhotoMOSFET.png

Introduction to PhotoMOSFET Relays

What is a Photo MOSFET Relay?

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

Introduction to PhotoMOSFET Relays.png


  • 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

Introduction to PhotoMOSFET Relays2.png

Features / Advantages / Disadvantages

Advantages vs. Reed Relay

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


  • 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 car.png

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


  • 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 Equipmentmri scanner.png

  • 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

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Our expert(s):

Dennis de la Roy Dennis de la Roy
Please contact Dennis with any questions or business opportunities relating to electronic Components of Heynen. We love to be involved in developing new solutions and bringing these to the Dutch market. Contact form dennis.delaroy@heynen.nl
+31 (0)485 55 09 37

Johan De Ceuster Johan De Ceuster
Please contact Johan with any questions or business opportunities relating to Electronic Components and RF. We love to be involved in developing new solutions and bringing these to the Belgian and Luxembourg market. Contact form johan.de.ceuster@heynen.be
+32 (0)11 60 09 10

Marcel van Venrooij Marcel van Venrooij
Please contact Marcel with any questions or business opportunities relating to Electronic Components. We love to be involved in developing new solutions and bringing these to the Dutch market. Contact form marcel.vanvenrooij@heynen.nl
+31 (0)485 55 09 18

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