Optocoupler Opto-Iscolator Chip PC817 (5 pack)

The PC817 is an generic optocoupler (or opto-isolator) IC commonly used to electrically isolate different parts of a circuit. It uses an LED and a phototransistor to transmit signals across an isolation barrier, which protects sensitive components from high voltage or noisy signals. The PC817 is packaged in a DIP-4 form factor, making it compatible with through-hole PCB designs and breadboards.

Key Specifications for PC817

General Specifications

1. Type: Optocoupler with a phototransistor output
2. Package: DIP-4 (Dual Inline Package, 4 pins)
3. Isolation Voltage: 5,000 Vrms between input and output
4. Current Transfer Ratio (CTR): Typically 50% to 600%, depending on the model variant

Electrical Characteristics

1. Input LED Forward Voltage (V_F): 1.2 V to 1.4 V at 20 mA
2. LED Forward Current (I_F): Maximum 50 mA
3. Collector-Emitter Voltage (V_CE): 35 V (max) on the output phototransistor
4. Collector Current (I_C): Up to 50 mA

Performance Characteristics

1. Switching Speed: ~4 µs to 18 µs, suitable for low- to medium-speed signal applications
2. Current Transfer Ratio (CTR): The efficiency of the LED to phototransistor transfer, with values that vary by part; standard PC817 models range between 50% to 600%
3. Isolation Voltage: 5,000 Vrms, providing excellent protection between low- and high-voltage sections of a circuit

Pin Configuration (DIP-4)

1. Pin 1 (Anode): LED anode (input side)
2. Pin 2 (Cathode): LED cathode (input side)
3. Pin 3 (Emitter): Phototransistor emitter (output side)
4. Pin 4 (Collector): Phototransistor collector (output side)

Key Features

1. Electrical Isolation: Provides effective isolation between control and power circuits, reducing interference and protecting sensitive components
2. Compact DIP-4 Package: Easy to integrate into designs needing electrical isolation
3. Wide CTR Range: Multiple CTR options for different needs, enhancing design flexibility
4. Reliable Signal Transfer: Supports low- and medium-speed digital and analog signal isolation

Applications

1. Switching Power Supplies: Isolates feedback signals between high-voltage and low-voltage sections
2. Microcontroller Interface Protection: Prevents backflow of high-voltage or noise into sensitive digital systems
3. Signal Isolation: Used for interfacing between high-power loads and low-voltage logic in industrial controls
4. Relay Driving and Motor Control: Allows microcontrollers to control higher-power relays or motors safely

The PC817 is widely used in power electronics, industrial controls, and embedded systems where safe electrical isolation is critical for both signal integrity and device protection.