Fast & free stop-desk delivery from 4000 DA | Flexible payment | Technical support for your builds
BinaryTech DZ

Optocouplers

37 results

Optocouplers and optotriacs to galvanically isolate a low-voltage control signal from a power circuit or the mains: PC817, 4N35, MOC3021, TLP250, 6N137 and isolation modules.

Related categories

LEDs, Matrices, IR and 7-Segment DisplaysDisplay ModulesLDR Photoresistors
37 results

37 results

123

Choosing an optocoupler by output type

An optocoupler transmits a signal through light: an infrared LED on one side, a phototransistor, a photodarlington or a triac on the other. Both sides remain electrically separated, which protects a microcontroller from a power stage or a circuit connected to the mains. The choice is made first on the type of output.

  • Transistor output — PC817, PC814, PC123, TLP521-1, 4N35, 4N37, CNY17: isolate a logic signal, a feedback signal or a regulation loop.
  • Triac output — MOC3021, MOC3023, MOC3051 without zero-cross detection, or MOC3041, MOC3061, MOC3083 as zero-cross: drive a power triac on the mains.
  • Isolated gate driver — TLP250, TLP350: drive a MOSFET or an IGBT in a chopper or an inverter.
  • Fast logic — 6N137, TLP113, TLP155E: isolated data links where speed matters.

Next check the package, through-hole DIP for breadboard builds or SMD like the PC17K1C, the PC814BS and the TLP181GB, then the number of channels (TLP521-2, 2 or 4-channel isolation modules). Finally look at the CTR, the ratio between the output current and the current in the input LED: a low CTR requires more current on the control side. A series resistor with the LED is still essential. The Optoelectronics category completes these references.

Frequently asked questions

What is the difference between a transistor-output optocoupler and an optotriac ?

A transistor-output optocoupler, such as the PC817 or the 4N35, transmits a low-current continuous signal. An optotriac such as the MOC3021 or the MOC3061 is used to trigger the gate of a power triac on an AC load, it does not replace the triac itself.

Zero-cross or non zero-cross to drive a triac ?

A zero-cross model (MOC3041, MOC3061, MOC3083) only switches at the zero crossing of the sine wave: fewer parasitics, ideal for a resistive load such as a heater or lighting. A non zero-cross model (MOC3021, MOC3023, MOC3051) switches at any point, which is needed for phase dimming.

PC817 or 4N35, which one to choose ?

The PC817 comes in a 4-pin package and is used for most simple signal isolation needs. The 4N35 and 4N37 come in 6-pin packages with the phototransistor base accessible, which allows adding a base-emitter resistor to stabilize operation or reduce sensitivity to noise.

Which component should drive a power MOSFET or IGBT ?

A PC817 has neither the speed nor the output current needed. You need an isolated gate driver such as the TLP250 or the TLP350, designed to quickly charge and discharge the gate capacitance while keeping the control and power sides isolated.

Can I pick up my order in store ?

Yes, pickup is available at the store in Bab Ezzouar, Algiers.