4N27TM

Overview

The 4N27TM is a high-speed optocoupler manufactured by onsemi, featuring an infrared-emitting GaAs LED coupled to a silicon NPN phototransistor. It provides electrical isolation with a dielectric strength of 7500 Vrms. The device includes a base terminal for the phototransistor, allowing for adjustable sensitivity and faster switching speeds compared to baseless variants. Packaged in a standard 6-pin DIP configuration, it is designed for robust performance in industrial and commercial applications requiring reliable signal transmission across isolated circuits.

Feature Summary

• Integrated base terminal on the phototransistor for enhanced speed control and sensitivity adjustment
• High dielectric isolation voltage ensuring safety in high-voltage circuit separation
• Infrared LED emitter paired with silicon NPN detector for efficient optical coupling

Applications

• Industrial process control systems
• Computer peripheral interface isolation
• Power supply feedback loops

Procurement Notes

Verify the specific suffix 'TM' against the manufacturer's current datasheet to confirm package type and tape-and-reel specifications. Ensure the component meets required isolation voltage ratings for your specific application safety standards. Cross-reference the date code and lot number for quality assurance. Confirm that the 6-DIP package dimensions align with your PCB footprint requirements before finalizing procurement orders.

Selection Notes

Select this component when base-driven speed improvement is necessary over standard baseless optocouplers. Consider the CTR (Current Transfer Ratio) variations at different forward currents during design. Evaluate the isolation voltage requirements against the 7500 Vrms rating. Compare propagation delay specifications if high-speed digital isolation is critical for the system timing constraints.

Part Context

This part belongs to onsemi's portfolio of intelligent power and sensing technologies, specifically within the discrete semiconductor category. It serves as a fundamental building block for galvanic isolation in mixed-signal environments. The product line supports various industrial and automotive applications where reliable signal transfer between low-voltage control logic and high-voltage power stages is essential.

Replacement Considerations

Check for direct pin-compatible substitutes such as the 4N25 or 4N26 series from onsemi or other manufacturers like Vishay or Broadcom. Verify that replacement parts meet or exceed the original isolation voltage and CTR specifications. Ensure the replacement package matches the 6-DIP form factor for seamless integration into existing designs.