PC817 Opto Isolator Optocoupler IC- DIP

PC817 Optocoupler / Opto-Isolator IC — DIP

The PC817 is a single-channel photocoupler (optocoupler) that electrically isolates two circuits. It contains an infrared LED on the input side and a phototransistor on the output side. When current flows through the LED, it produces infrared light that turns on the phototransistor, transferring the signal without a direct electrical connection.

IC Description:

The PC817 is commonly used for signal isolation between high- and low-voltage circuits, such as microcontroller interfaces, power supplies, relay drivers, and industrial control circuits. It is typically available in a 4-pin DIP package.

Pin Configuration

          PC817
       ┌─────────┐
Pin 1 ─┤ Anode   │
Pin 2 ─┤ Cathode │
Pin 3 ─┤ Emitter │
Pin 4 ─┤Collector│
       └─────────┘

Main Features

• Single-channel optocoupler
• Infrared LED + phototransistor
• Electrical isolation between input and output
• 4-pin DIP package
• Low input current operation
• High isolation voltage
• Suitable for digital signal isolation
• Helps protect low-voltage control circuits from higher-voltage circuits

Typical Specifications

Note: PC817 is produced in several CTR grades and by multiple manufacturers, so exact values such as CTR, isolation voltage, maximum collector current, and temperature range should be taken from the datasheet for the specific PC817 part.

Working Principle

Input circuit                         Output circuit
     +V                                     +V
      |                                      |
    Resistor                              Load
      |                                      |
      ▼                                      ▼
   ┌───────┐     Light                 ┌─────────┐
   │ IR LED│  ───────────────►         │   C     │
   └───────┘                            │  ───    │
      │                                 │   E     │
     GND                                └─────────┘
                                           |
                                          GND

The input LED and output transistor are optically coupled but electrically isolated. This makes the PC817 useful when a microcontroller or other low-voltage circuit needs to communicate with a circuit operating at a different voltage or electrical ground.