4N23

Overview

The 4N23 is a single-channel transistor output optocoupler manufactured by TT Electronics/Optek Technology. It integrates an infrared emitting diode and an NPN silicon phototransistor within a hermetically sealed TO-78-6 metal can package. The device provides electrical isolation with a rated insulation voltage of 1000 Vrms. Key electrical parameters include a maximum collector-emitter voltage of 35 V, a maximum collector current of 50 mA, and a typical forward voltage of 1.3 V at a forward current of 10 mA. The unit features a minimum current transfer ratio of 20% and operates within a temperature range of -55°C to +125°C.

Feature Summary

• Hermetically sealed construction in a TO-78-6 metal can package for environmental protection
• Integrated NPN silicon phototransistor output for signal transmission
• High isolation voltage rating of 1000 Vrms between input and output circuits

Applications

• Industrial control systems requiring galvanic isolation
• Solid-state relay driver circuits
• Logic-to-device interface isolation

Procurement Notes

Verify the specific suffix designation when ordering, as variants such as 4N23A or 4N23TXV may exist with different performance specifications or radiation hardness levels. Confirm that the required package type matches the TO-78-6 form factor. Ensure the selected variant meets the thermal and voltage requirements of the target application before finalizing procurement.

Selection Notes

Select this component when a robust, hermetically sealed optocoupler is required for high-reliability applications. The 4N23 offers a balance of moderate speed and high isolation voltage suitable for general-purpose digital isolation. Consider the 20% minimum current transfer ratio when designing base drive circuits to ensure saturation under all operating conditions.

Part Context

The 4N23 belongs to the widely recognized 4Nxx series of transistor output optocouplers produced by TT Electronics/Optek Technology. This family is characterized by its use of a standard TO-78 metal can package, which distinguishes it from modern plastic-packaged alternatives. The series is commonly utilized in legacy designs and industrial environments where long-term reliability and hermetic sealing are prioritized over miniaturization.

Replacement Considerations

Direct replacements include the 4N22 and 4N24, which share similar pinouts and packaging but differ in current transfer ratio specifications. Verify compatibility with the 4N23A variant if higher CTR is required.