Description

The 4N25 Optocoupler is a standard phototransistor-based optoisolator designed to provide electrical isolation between input and output circuits. It integrates an infrared LED and a silicon NPN phototransistor inside a compact DIP-6 package, enabling signal transfer through light rather than direct electrical connection.

This design allows the 4N25 to effectively protect low-voltage control circuits from high-voltage or noisy environments, making it a critical component in many electronic systems. It supports high isolation voltage (up to 5kV), ensuring safe and reliable operation in demanding applications.

The device features a single-channel transistor output with a typical current transfer ratio (CTR) of around 20%, allowing it to interface easily with logic circuits and microcontrollers.

With a collector-emitter voltage up to 70V and fast switching response (microsecond range), the 4N25 is suitable for both analog and digital signal isolation tasks.

Its standard DIP-6 package ensures easy mounting on PCBs and compatibility with breadboards, making it ideal for prototyping and production designs.

Key Applications

• Microcontroller input/output isolation (Arduino, PIC, etc.)
• Switch-mode power supplies (SMPS feedback circuits)
• AC mains detection and control
• Industrial automation and control systems
• Signal isolation in communication circuits
• Relay driving and noise isolation

Key Features

• Type: Optocoupler / Optoisolator
• Output: NPN Phototransistor
• Channels: 1
• Package: DIP-6 (through-hole)
• Isolation voltage: up to 5kV
• CTR: ~20%
• Collector-emitter voltage: up to 70V
• Low noise and high reliability