4N25X – ISOCOM

The 4N25X, manufactured by ISOCOM, is a gallium arsenide (GaAs) infrared emitting diode optically coupled to a silicon NPN phototransistor, housed in a standard 6-pin dual-in-line package (DIP). This optocoupler provides a high isolation voltage of 5.3 kVrms, enabling electrical isolation between input and output circuits. The device features a base connection on the phototransistor, allowing for external gain control and improved switching speed characteristics. Key parameters include a typical current transfer ratio (CTR) of 20% at an input current of 10mA and a collector-emitter voltage of 30V. The 4N25X is designed for applications requiring electrical isolation, such as signal transmission in noisy environments, power supply isolation, and digital logic isolation. Its operating temperature range is typically -55°C to +100°C.