Optocoupler Chip
PC817 (Photoelectric optocoupler, transistor output)
Channels Available
2, 4, or 8 (depending on board version)
Driving Port Signal Voltage
3.6V – 24V DC
Output Port Voltage Port
3.6-30V
Input Side (Control Side)
– Each channel has its own input (IN1, IN2, etc.)
– Active low triggering (usually GND triggers LED inside the optocoupler)
– Input resistor onboard for current limiting
– Isolation voltage: 3.75 kV RMS
Output Side
– Open-collector transistor output (NPN)
– Output can switch external voltage (commonly 3.3V or 5V logic, sometimes higher depending on load)
– Collector and emitter pins are broken out per channel
– Logic level conversion supported (e.g., 5V → 3.3V isolation)
Power Supply
– Board VCC: 3.6V – 30V DC (powers input side and internal LEDs)
– Output side isolated, requires separate pull-up or external voltage supply
Pins (Typical 4/8 Channel Board Layout)
– VCC: Power for input side (3.6–30V)
– GND: Input ground
– IN1, IN2 … IN8: Channel input signals
– OUT1, OUT2 … OUT8: Channel outputs (open collector)
– GND (output side): Ground for output circuit
Features
– Electrical isolation between microcontroller/logic and high-voltage side
– Prevents noise, surges, or spikes from damaging low-voltage circuits
– Can be used for switching, signal isolation, PLC interfacing, level shifting
– High reliability, long service life
Typical Applications
– Microcontroller I/O isolation
– PLC signal isolation
– Driving relays, solenoids, or MOSFETs with isolation
– Logic level conversion between different voltage domains
– Protecting Arduino, ESP32, STM32, Raspberry Pi, etc. from higher-voltage circuits