4N25 Optocoupler Phototransistor IC DIP 8 Package

4N25 Optocoupler Phototransistor IC DIP 8 Package 

The 4N25 is a classic and highly reliable phototransistor-based optocoupler designed to provide electrical isolation between low-voltage control circuits and high-voltage or noisy environments. Inside the IC, an infrared emitting diode (IRED) is optically coupled to a silicon NPN phototransistor, allowing signal transfer without any physical electrical connection. This isolation helps protect sensitive microcontroller or logic circuits from voltage spikes, ground loop issues, and electromagnetic interference.

The DIP-8 package offers additional flexibility compared to the standard DIP-6 version. It provides extra pins for accessing the base of the phototransistor, enabling adjustments of gain, speed, or noise immunity through external components. The spacing of the DIP-8 package makes it robust for through-hole soldering and ideal for prototyping, testing, and industrial applications where reliability and insulation distance matter.

The device supports moderate switching speeds, making it suitable for digital as well as low-frequency analog signal isolation. With a typical isolation voltage rating around 5 kV peak, the 4N25 offers dependable protection in mixed-signal environments, ensuring safe and noise-free signal transfer.

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Features:-

• Isolation test voltage 5000 VRMS
• Interfaces with common logic families
• Input-output coupling capacitance < 0.5 pF
• Industry standard dual-in-line 6 pin package
• Compliant to RoHS directive 2002/95/EC and in accordance to WEEE 2002/96/EC

Applications

• Microcontroller to high-voltage circuit isolation
• SMPS feedback circuits
• Relay and TRIAC driver isolation
• Signal level shifting
• Industrial automation systems
• Noise-sensitive instrumentation
• Protection of sensitive ADC/DAC circuits
• Communication between different ground domains

4N2 Series Datasheet