TCDT1121

Overview

The TCDT1121 is a single-channel transistor output optoisolator manufactured by Vishay Semiconductor Opto Division. It features an NPN phototransistor output with a maximum collector-emitter voltage of 70V and a peak collector current of 50mA. The device provides high isolation capability with an insulation voltage of 5000Vrms. Key electrical parameters include a minimum current transfer ratio of 40% at a forward current of 60mA, a forward voltage of 1.6V, and a reverse voltage rating of 5V. The package supports through-hole mounting in a 6-DIP configuration.

Feature Summary

• Provides galvanic isolation between input and output circuits using an infrared LED and NPN phototransistor pair.
• Offers high dielectric strength with a 5000Vrms insulation voltage rating for safety-critical applications.
• Designed for through-hole integration within a compact 6-DIP package structure.

Applications

• General-purpose signal isolation in industrial control systems
• Interface circuits for microprocessor-based logic systems
• Switching power supply feedback loops

Procurement Notes

Verify the specific suffix and RoHS compliance status against the manufacturer's latest datasheet before ordering. Confirm that the 6-DIP package dimensions match your PCB footprint requirements. Ensure the operating temperature range of -55°C to 100°C aligns with your system's thermal environment. Check for any obsolete status or lifecycle changes directly from Vishay Semiconductor Opto Division official channels.

Selection Notes

Select this component when high isolation voltage is required alongside standard transistor output switching speeds. Consider the 70V collector-emitter voltage limit for load compatibility. Evaluate the 40% minimum current transfer ratio to ensure sufficient drive capability for downstream logic levels. Verify that the 60mA forward current rating suits your LED drive circuit design constraints.

Part Context

The TCDT1121 belongs to Vishay's family of transistor output optoisolators designed for general-purpose isolation tasks. It shares functional similarities with other models in the series but is distinguished by its specific voltage ratings and DIP-6 packaging. This part serves as a fundamental building block for creating electrically isolated signal paths in electronic designs requiring robust noise immunity.

Replacement Considerations

Consult Vishay's official cross-reference documentation for direct pin-compatible substitutes. Verify that any alternative maintains the 5000Vrms isolation rating and 70V output voltage specification. Ensure the replacement device matches the 6-DIP package form factor and through-hole mounting requirements.