4N33 Optocoupler IC

4N33 Optocoupler IC 

The 4N33 is a phototransistor-based optocoupler designed to provide safe and reliable electrical isolation between low-voltage control circuitry and high-voltage or noisy environments. It contains an infrared LED and a phototransistor output housed inside a DIP-6 package.

A key characteristic of the 4N33 is its base pin access, allowing external biasing of the phototransistor. This enables customizable response adjustment, making the device suitable for applications requiring signal amplification, variable gain, or controlled switching.

The device is widely used in microcontroller interfaces, switching power supplies, industrial controllers, data communication systems, and automation circuits where isolation and noise immunity are critical.

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Features

• Infrared LED and NPN phototransistor in a 6-pin DIP package
• Base pin available for gain control
• High isolation voltage (typically 5000 Vrms)
• Good noise immunity
• Low input LED current requirements
• Compatible with TTL, CMOS, and microcontrollers
• Wide operating temperature range
• Reliable long-life optical coupling
• Compact size for PCB mounting

Specifications:

• Optocoupler Case Style : DIP
• Forward Current If Max : 60mA
• Collector Emitter Voltage V(br)ceo : 55V
• No. of Channels : 1 Channel
• Isolation Voltage : 5.3kV
• No. of Pins : 6 Pins

Applications

• Microcontroller-to-high-voltage interfacing
• Power supply feedback and regulation
• Industrial automation systems
• Signal isolation in data communication
• Triac or transistor driver circuits
• Relay replacement in low-power switching
• Motor control and protection circuits
• Sensor signal isolation
• PLC input/output isolation
• Noise isolation for communication lines