What Is the 4N35? Optocoupler: Pinout, Base Pin and Uses
The 4N35 is a classic phototransistor-output optocoupler. It is similar to the PC817 but 6-pin, and the output transistor's base is also brought out. It isolates two circuits by ~5000 V; it is used for signal isolation and level shifting. Pinout DIP-6: 1 Anode, 2 Cathode, 4 Emitter, 5 Collector, 6 Base. A current-limiting resistor on the input LED is a must.
The 4N35 is a classic phototransistor-output optocoupler. It is similar to the PC817 but 6-pin, and the output transistor's base is also brought out (for sensitivity/speed tuning). For the concept, see what is an optocoupler.
What is the 4N35 used for?
Isolating a microcontroller from a high-voltage/noisy side, signal isolation, level shifting and breaking ground loops. The base pin can be used with a resistor for noise suppression or gain adjustment (usually left open).
4N35 pinout (DIP-6)
| Pin | Function |
|---|---|
| 1 | Anode (LED +) |
| 2 | Cathode (LED −) |
| 3 | NC |
| 4 | Emitter |
| 5 | Collector |
| 6 | Base |
Specifications
| Parameter | Value |
|---|---|
| Type | Phototransistor optocoupler |
| Isolation | ~5000 Vrms |
| CTR | ~100% (min) |
| Channels | 1 |
Watch out
A current-limiting resistor on the input LED is a must. The phototransistor is slow; if you need high speed use the 6N137.
Equivalents
- PC817: a common 4-pin optocoupler.
- 4N25 / 4N26 / 4N37: the close family.
- PC847: a four-channel part.
Find it in our catalog
Use the 4N35 search.