THDB421A - THDB Series

Series: THDB
Questions? Contact Littelfuse Support
External overview image
Roll Over to Zoom
Disclaimer Notice

Littelfuse products are not designed for, and shall not be used for, any purpose (including, without limitation, automotive, military, aerospace, medical, life-saving, life-sustaining or nuclear facility applications, devices intended for surgical implant into the body, or any other application in which the failure or lack of desired operation of the product may result in personal injury, death, or property damage) other than those expressly set forth in applicable Littelfuse product documentation. Warranties granted by Littelfuse shall be deemed void for products used for any purpose not expressly set forth in applicable Littelfuse documentation. Littelfuse shall not be liable for any claims or damages arising out of products used in applications not expressly intended by Littelfuse as set forth in applicable Littelfuse documentation. The sale and use of Littelfuse products is subject to Littelfuse Terms and Conditions of Sale, unless otherwise agreed by Littelfuse. "Littelfuse" includes Littelfuse, Inc., and all of its affiliate entities.

The THDB Series combines accurate timing circuitry with high power, solid-state switching. It can switch motors, lamps, and heaters directly without a contactor. You can reduce labor, component cost, and increase reliability with these small, easy-to-use, THDB Series timers.


Operation (Delay-on-Break)
Input voltage must be applied before and during timing. Upon closure of the initiate switch, the output energizes. The time delay begins when the initiate switch is opened. The output remains energized during timing. At the end of the time delay, the output de-energizes. The output energizes if the initiate switch is closed when input voltage is applied.
Reset: Reclosing the initiate switch during timing resets the time delay. Loss of input voltage resets the time delay and output.

Check Stock Order Samples

Product Literature

For Technical Questions

Call +1 800-832-3873 or email us at relays@littelfuse.com 

Property (Mouseover for details) Value
Input Voltage (V) 120 V ac
Input Tolerance (%) ±20%
Input AC Line Frequency (Hz) 50/60
Output Type Solid state
Output Form NO - closed before and during timing
Output Load Rating (VA) 6 A steady state; 60 A inrush
Minimum Output Load Current (A) 100
Output Voltage Drop (V) ≅2.5 V @ rated current
Time Delay Range 0.1 - 10 s externally adjustable
Time Delay Tolerance (%) ±1%
Reset Time (ms) ≤150
Initiate Time (ms) ≤20
Repeat Accuracy (%) ±0.5% or 20 ms whichever is greater
Setpoint vs Ambient Temperature and Operating Voltage (%) ≤±2%
Undervoltage Trip Voltage 0.1 - 10 s externally adjustable
Open State Leakage Current (A) ≅5 @230 V ac
Insulation Resistance ≥100
Dielectric Breakdown ≥2000V terminals to mounting surface
Circuitry Encapsulated
Power Consumption ≤2 VA
Termination Type 0.25 in. (6.35 mm) male quick connect terminals
Mounting Method Surface mount with 1 #10 (M5 x 0.8) screw
Operating Temperature -40° to 60°C (-40° to 140°F)
Storage Temperature (F/C) -40° to 85°C (-40° to 185°F)
Humidity 95% relative : non-condensing
Dimensions 2 H x 2 W in. (50.8 x 50.8 mm)
Weight (lbs/g) 0 Kg
Dimensions 2 H x 2 W in. (50.8 x 50.8 mm)

To request product environmental information, please complete the Product Environmental Information Request Form.