Introduction
The PC817 optocoupler (also called a photocoupler) offers reliable electrical isolation between input and output circuits while enabling signal transmission via light. Featuring a built-in infrared LED and phototransistor, the PC817 ensures galvanic isolation, protecting sensitive electronics from voltage spikes and noisy interference. It can be used in microcontroller projects, industrial automation, or power electronics. The PC817 delivers performance, safety, and signal integrity.
Key Features
- High Isolation Voltage – Up to 5,000 V RMS ensures robust galvanic isolation, protecting low-voltage control circuits from high-voltage transients.
- Fast Switching Speed – With a turn-on time of approximately 3 µs and turn-off time near 35 µs, ideal for digital communication and logic-level interfacing.
- Compact DIP-4 Package – Space-saving form factor compatible with standard DIP sockets and PCB layouts.
- Low Input Current – LED forward current typically around 20 mA, maintaining energy efficiency in tight-power designs.
- High CTR (Current Transfer Ratio) – Efficient optoelectronic coupling ratio (~50% to 600%), ensuring ample drive for downstream circuits.
Technical Specifications
| Specification | Value / Range |
|---|---|
| Input LED | Forward Voltage (V_F): 1.2 V (typical) |
| Forward Current (I_F): 1–20 mA | |
| Isolation Voltage | 5,000 V RMS (min) |
| Output Phototransistor | Collector-Emitter Voltage (V_CE): 35 V (max) |
| Collector Current (I_C): 50 mA (max) | |
| Collector-Emitter Saturation Voltage (V_CESat): ~0.3 V | |
| Current Transfer Ratio | 50 % – 600 % (depending on test conditions) |
| Response Times | Turn-On Delay: ~3 µs, Turn-Off Delay: ~35 µs |
| Package | 4-Pin DIP (Dual-In-Line), 6.4 mm pitch |
| Temperature Range | Operating: –30 °C to +100 °C, Storage: –55 °C to +125 °C |
Applications
- Microcontroller and Logic Interfacing – Safely transmit signals between high-voltage parts and low-voltage digital electronics (e.g., Arduino, Raspberry Pi).
- Industrial Power and Motor Control – Protect control boards in systems with AC mains switching, inverter drives, or induction motors.
- Switch-Mode Power Supplies (SMPS) – Provide feedback isolation between the secondary and primary sides of power converters.
- Over-Voltage/ Surge Detection – Detect faults or dangerous line conditions while keeping control systems shielded.
- Signal Isolation in Telecommunication – Reduce ground-loop interference in communication systems, measurement equipment, and modems.
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