PC817 4-Channel Optocoupler Isolation Module

Specifications

Core Components

• Optocouplers: 4 × PC817 optocoupler
  (Each contains an infrared LED + phototransistor for signal isolation)

Purpose

• Provides electrical isolation between the input and output sides
• Protects microcontrollers and sensitive circuits from noise, high voltage, or spikes
• Commonly used for isolating:
  • Digital signals
  • Control signals
  • Communication lines

Electrical Characteristics (Typical, per Channel)

• Input (LED) Forward Voltage: ~1.2 V
• Input Forward Current: max ~20 mA
• Output Phototransistor Collector‑Emitter Voltage: max ~30–35 V
• Current Transfer Ratio (CTR): typically 20%–50%

Module Input

• Channels: 4 isolated input channels
• Signal Type: digital (logic/TTL)
• Inputs from microcontrollers (5V logic) or other driving circuits
• Often includes input current‑limiting resistors on board

Module Outputs

• Open‑collector phototransistor outputs (active when the input LED is driven)
• Typically requires an external pull‑up resistor on the output side (sometimes included on board)

Power and Supply

• Some variants may require a module VCC to power pull‑ups
• Input and output sides are galvanically isolated
• Isolation voltage rating (between input and output):
  • Typically ≥ 3 kV (3000 V) (depends on board design)

Interface

• Standard 2.54 mm (0.1″) header pins
• Typical pin layout:
  • 4x Inputs (IN1–IN4)
  • 4x Outputs (OUT1–OUT4)
  • GND / VCC (depending on version)