4N35

Overview

The Lite-On 4N35 is a single-channel transistor output optocoupler housed in a 6-pin PDIP package. It features an infrared LED coupled to an NPN phototransistor with an accessible base terminal. Key electrical parameters include a maximum collector-emitter voltage of 30V, a peak forward current of 60mA, and a typical forward voltage of 1.2V. The device provides an isolation voltage of 3550Vrms and supports a minimum current transfer ratio of 100% at 10mA input. Operating temperatures range from -55°C to 100°C, with rise and fall times typically around 10µs.

Feature Summary

• Provides electrical isolation between input and output circuits using optical transmission via an infrared LED and phototransistor.
• Includes an exposed base terminal on the phototransistor to allow for external biasing or speed enhancement.
• Ensures high safety isolation with a rated insulation voltage of 3550Vrms between input and output sections.

Applications

• Signal isolation in industrial control systems
• Power supply feedback loop isolation
• Microprocessor interface circuitry
• Solid-state relay driver circuits

Procurement Notes

Verify the specific suffix (e.g., standard DIP vs. SMD variants) when ordering, as packaging and pin configuration differ significantly between through-hole and surface-mount versions. Confirm RoHS compliance status for the specific batch if required by project specifications. Ensure the selected variant matches the required isolation voltage rating for the target application environment.

Selection Notes

Select this component for applications requiring basic galvanic isolation with a low-cost solution. The accessible base pin allows designers to optimize switching speed or sensitivity by adding external resistors. Consider the 10µs propagation delay when designing for high-frequency signal transmission, as it may limit performance in fast-switching digital interfaces compared to faster logic-output optocouplers.

Part Context

The 4N35 belongs to the widely used 4N3X series of general-purpose optocouplers manufactured by Lite-On Inc. This series is characterized by its robustness and long-standing availability in electronic design. The standard 4N35 variant specifically utilizes a 6-pin dual in-line package, distinguishing it from surface-mount counterparts like the 4N35S-TA1 which use 6-SMD packages.

Replacement Considerations

The 4N35-300E from Broadcom Limited is documented as a parameter-equivalent substitute. Other similar options include the 4N35SM and 4N35SR2M from onsemi. Verify pinout compatibility and thermal characteristics before substituting to ensure circuit integrity.