4N25 6 Pin PhotoTransistor Optocoupler

Overview

The 4N25 is a versatile 6-pin optocoupler that provides electrical isolation between input and output circuits. It consists of a gallium arsenide infrared LED and a silicon NPN phototransistor. This component is essential for protecting sensitive control circuits from high voltages, noise, and ground loops. Whether you're building power supplies, microcontroller interfaces, or industrial controls, the 4N25 ensures safe and reliable signal transfer.

Key Features

• Electrical Isolation: Provides up to 2500 Vrms of isolation, protecting low-voltage logic from high-voltage transients.
• Phototransistor Output: Directly compatible with digital logic and microcontroller inputs.
• Wide Operating Temperature: Functions reliably from -55°C to +100°C.
• Industry Standard: Pin-compatible with other common optocouplers, making it a drop-in replacement.
• High-Speed Switching: Suitable for applications up to 300 kHz.

Technical Specifications

• Package: 6-pin DIP
• Input: Infrared LED (1.2V forward voltage, 60 mA max forward current)
• Output: NPN Phototransistor (30V collector-emitter voltage, 50 mA collector current)
• Isolation Voltage: 2500 Vrms
• Current Transfer Ratio (CTR): 20% to 50% at 10 mA input
• Operating Temperature: -55°C to +100°C
• Switching Speed: Rise/fall time typically 2 µs and 3 µs respectively

Applications & Use Cases

• Microcontroller Interfacing: Isolate and protect GPIO pins from external noise and voltage spikes.
• Power Supply Feedback: Provide feedback from high-voltage outputs to low-voltage controllers.
• AC/DC Motor Control: Drive TRIACs or relays for motor control with safe isolation.
• Industrial Automation: Use in PLCs and sensor interfaces to prevent ground loops.
• Signal Isolation: Separate audio or data signals to eliminate hum and interference.

What's Included

• 1x 4N25 6-Pin Phototransistor Optocoupler

Compatibility

• Works with all microcontrollers (Arduino, Raspberry Pi, ESP32, PIC, etc.)
• Can drive relays, TRIACs, and other power devices with appropriate circuitry
• Replaces common equivalents: PC817, 4N35, 4N36, and similar optocouplers

MOKWN Recommendation

For Egyptian electronics enthusiasts and professionals, the 4N25 is a fundamental component for safe circuit design. We recommend keeping a few in your parts drawer for prototyping and production. Pair it with a resistor to limit LED current and ensure reliable operation. For higher isolation or different CTR requirements, check our full range of optocouplers.