FSC4N35 / 4N35 (ON) White Optocoupler DIP-6 Code: 15790043

The FSC 4N35 is a widely used, 6-pin general-purpose optocoupler (optoisolator) manufactured by Fairchild Semiconductor (now part of onsemi). It is designed to transfer electrical signals between two isolated circuits using light, effectively protecting low-voltage components (like microcontrollers) from high-voltage spikes or electrical noise.

Core Specifications

• Component Type:Optocoupler with an infrared LED input and a phototransistor output (with base connection).
• Isolation Voltage:Up to 3550 Vrms to 5300 Vrms (depending on the exact manufacturer rating).
• Current Transfer Ratio (CTR):Minimum 100%
• Maximum Collector-Emitter Voltage:30 V.
• Maximum Forward Current (LED):60 mA (Continuous).
• Operating Temperature Range:-55°C to +100°C.

Pinout Configuration

1. Anode:Positive input for the internal LED.
2. Cathode:Negative input / ground for the internal LED.
3. NC:No Connection.
4. Emitter:Emitter of the output phototransistor.
5. Collector:Collector of the output phototransistor.
6. Base:Base of the phototransistor (can be left floating or used to adjust sensitivity).

Common Applications

• Microcontroller I/O Isolation:Interfacing Arduino, ESP32, or Raspberry Pi pins to control higher voltage or AC-coupled circuits.
• Switch-Mode Power Supplies (SMPS):Providing safe feedback control across the primary and secondary sides.
• Motor Control & Relay Driving:Switching inductive loads without risking voltage back-feed.