PC817 Optocoupler (Opto-Isolator IC)

The PC817 Optocoupler provides electrical isolation between circuits using an infrared LED and phototransistor. It transfers signals across an isolation barrier while preventing high-voltage interference from damaging sensitive electronics.

Key Features

• Optical isolation between input and output
• 5000V isolation rating
• Infrared LED + phototransistor
• DIP-4 package
• Low cost isolation solution
• No electrical connection between sides
• Wide operating temperature range

Technical Specifications

Applications

• High-voltage isolation
• Switch-mode power supply feedback
• Motor drive isolation
• Noise suppression
• Microcontroller protection
• Ground loop elimination

Important Notes

• LED side needs current-limiting resistor like standard LED
• Phototransistor side needs pull-up resistor
• Switching speed limited (~4-18μs) – not for high-speed data
• CTR varies with temperature and LED current
• Can be used as solid-state relay for low-current switching