ST32

Overview

The Littelfuse ST32 is a standard bidirectional DIAC trigger thyristor housed in the DO-214 (SMD) package. It serves as a full-wave semiconductor switch that transitions from a blocking state to conduction when applied voltage exceeds its breakover threshold, functioning for either polarity. The device features a breakover voltage range of 27V to 37V and supports a pulse on-state current of 2A at 120 pulses per second with a 10µs width. Operating within a junction temperature range of -40°C to +125°C, it utilizes high-temperature soldered die attachment for reliability.

Feature Summary

• Bidirectional triggering capability for AC phase control applications
• High-temperature bonded die attachment for improved thermal stability
• Glass-passivated junctions to resist contamination and ensure long-term parameter stability

Applications

• Lamp dimming circuits
• Universal motor speed control systems
• Heat control regulation
• Solid state ballast lighting controls

Procurement Notes

Verify the specific suffix against the manufacturer's selector table to confirm the exact breakover voltage tolerance required for the design. Confirm whether bulk or tape-and-reel packaging is needed for the assembly process. Ensure the component meets RoHS compliance standards if applicable to the final product regulations.

Selection Notes

Select this component based on the required breakover voltage symmetry and peak current handling capabilities. Verify that the operating environment stays within the specified thermal limits and that the DO-214 package footprint matches the PCB layout constraints. Consider derating power dissipation if ambient temperatures exceed 40°C.

Part Context

This part belongs to the HTxxx & HTMxxx & STxxx series of Standard Bidirectional DIAC Triggers manufactured by Littelfuse. The ST prefix specifically denotes the surface-mount DO-214 package variant, distinguishing it from the axial lead HT series and the MINIMELF HTM series.

Replacement Considerations

Direct substitutes include HT-32 and HTM-32B for equivalent electrical characteristics in different packages. Cross-reference the DO-214 footprint compatibility before swapping between package types.