Q4008LH4

Triacs Overview

The Littelfuse Q4008LH4 is a Quadrac device, which integrates a triac and a diac trigger within a single package. It functions as a bidirectional AC switch controlled by gate polarity for main terminal voltage of either polarity. The component belongs to the Qxx08xx series and utilizes a TO-220-2 through-hole package with an electrically isolated tab rated at 2500V rms from the leads. Key electrical parameters include an RMS on-state current (It RMS) of 8 A, a rated repetitive off-state voltage (VDRM) of 400 V, and a maximum holding current (Ih) of 50 mA. The device operates within a temperature range of -40°C to +125°C.

Triacs Feature Summary

• Integrated Diac Trigger: Combines a triac and a diac in one package to eliminate external discrete components and assembly time.
• Electrical Isolation: Features a TO-220 package with 2500V rms isolation between leads and mounting surface, removing the need for separate insulators.
• Bidirectional Switching: Designed for AC switching and phase control applications requiring noise immunity.

Triacs Applications

• AC speed controls
• Temperature modulation controls
• Lighting controls

Triacs Procurement Notes

Verify the specific suffix 'H' against official Littelfuse documentation to confirm pinout configuration and isolation ratings. Ensure the selected variant matches the required thermal management specifications for the intended application environment.

Triacs Selection Notes

Select this component for applications requiring integrated gate triggering without external snubber networks or discrete diacs. Confirm that the 400V voltage rating and 8A current capacity align with the load requirements. Verify compatibility with the TO-220-2 footprint during PCB layout.

Triacs Part Context

This part belongs to the Teccor Quadrac family developed by Littelfuse. These devices are designed to simplify circuit design by replacing separate triac and diac assemblies. The Q4008LH4 specifically targets AC power control markets where reliability and reduced assembly complexity are prioritized.

Triacs Replacement Considerations

Consult Littelfuse datasheets for direct equivalents within the QxxxxLTx series. Verify pinout compatibility before substituting with other manufacturers' integrated triac-diac units.

Triacs FAQ

What is the primary advantage of using the Q4008LH4 over a standard triac?

It integrates a diac trigger inside the package, eliminating the need for external discrete components and reducing assembly time.

Is the Q4008LH4 suitable for high-noise environments?

Yes, it is designed for applications where noise immunity is required, such as lighting and speed controls.