HT35

Overview

The Littelfuse HT35 is a standard bidirectional DIAC trigger thyristor from the HTxxx series. It features a DO-35 axial leaded package and operates within a breakover voltage range of 30V to 40V at 25°C. The device supports a repetitive peak on-state current of 2A with a pulse width of 10μs. It functions by triggering from a blocking state to conduction when applied voltage exceeds its breakover threshold for either polarity. Thermal resistance is 100 °C/W junction-to-lead and 278 °C/W junction-to-ambient. Maximum operating and storage temperatures are +125°C.

Feature Summary

• Bidirectional full-wave switching capability for symmetrical triggering
• High reliability through glass passivated junction construction
• Lead-free matte-tin terminal finish compliant with environmental standards

Applications

• Phase control circuits for lamp dimming
• Universal motor speed control systems
• Heat control applications
• Solid state ballast lighting controls

Procurement Notes

Verify the specific package configuration required, as the HT35 designation corresponds to the DO-35 leaded style in this series. Confirm that the 30V to 40V breakover voltage range aligns with the circuit design requirements. Ensure thermal management strategies account for the specified junction-to-ambient resistance values during operation.

Selection Notes

Select the HT35 when a breakover voltage between 30V and 40V is necessary for triggering triacs or SCRs. Consider the DO-35 package if through-hole mounting is preferred over surface mount alternatives like the ST35. Evaluate the 2A peak current rating against the expected load currents in the phase control application to ensure adequate surge handling capacity.

Part Context

The HT35 belongs to the HTxxx & HTMxxx & STxxx series of standard bidirectional DIAC triggers manufactured by Littelfuse under the Teccor brand. This family offers various voltage characteristics ranging from 27V to 70V across different package types including MINIMELF, DO-35, and DO-214.

Replacement Considerations

Compatible substitutes within the same series include HT36A (32V to 40V) and HT36B (34V to 38V). For surface mount equivalents, consider the ST35 (DO-214 package) which shares identical electrical characteristics but utilizes a different physical footprint.