4N24TX

Overview

The 4N24TX is a high-reliability optically coupled isolator manufactured by TT Electronics/Optek Technology. It integrates an infrared emitting diode and an NPN silicon phototransistor within a hermetically sealed TO-78 metal can package. The device provides 1000VDC electrical isolation between input and output channels. Key electrical parameters include a maximum collector-emitter voltage of 35V, a DC forward current limit of 40mA, and a typical forward voltage of 1.3V. It features a minimum current transfer ratio of 100% at 10mA input current, with rise and fall times typically rated at 20µs each. The unit supports through-hole mounting and operates within a temperature range of -65°C to 125°C.

Feature Summary

• Hermetically sealed TO-78 metal can package designed for military and harsh environments
• High current transfer ratio ensuring efficient signal transmission
• Base contact provided on the phototransistor for conventional biasing applications
• Processed to MIL-PRF-19500 standards for enhanced reliability

Applications

• High-voltage isolation between input and output circuits
• Electrical isolation in electrically noisy or dirty industrial environments
• Isolation interfaces in medical equipment
• Signal coupling in office automation equipment

Procurement Notes

Verify that the specific suffix 'TX' confirms processing to MIL-PRF-19500 standards, as this denotes military-grade screening distinct from commercial variants. Confirm the presence of the base pin configuration if transistor biasing is required for the application circuit. Ensure the TO-78-6 lead frame compatibility matches the target PCB footprint. Check RoHS compliance status against project requirements, noting that military-specified parts may have different regulatory classifications than standard commercial components.

Selection Notes

Select the 4N24TX when high reliability and hermetic sealing are critical for long-term performance in extreme conditions. The provided base terminal allows for improved switching speed control compared to baseless configurations. Consider the 1000VDC isolation rating for safety-critical barrier applications. Evaluate the 100% minimum CTR requirement against drive current capabilities to ensure adequate noise margins. The wide operating temperature range supports deployment in uncontrolled environmental settings.

Part Context

This component belongs to the 4N22-24 series of high-reliability optocouplers produced by TT Electronics/Optek Technology. The series utilizes gallium arsenide infrared emitters paired with silicon phototransistors. The 4N24 variant specifically offers higher current transfer ratios compared to lower-performance models in the lineup. The TX suffix indicates adherence to rigorous military screening protocols, distinguishing it from standard commercial equivalents like the basic 4N24.

Replacement Considerations

Public confirmed substitute part numbers include 4N24 and 4N24ATXV.