Littlefuse Introduces New LST Varistor Series

By Chad Cox

Production Editor

Embedded Computing Design

March 09, 2021


Littlefuse Introduces New LST Varistor Series
(Image courtesy of Littlefuse)

Littelfuse introduced the LST Varistor series.

Constructed with a proprietary thermally protected varistor technology (TMOV) developed by Littelfuse, this new varistor incorporates both a built-in thermal disconnect function and electric arc shield. This provides additional robust protection to prevent catastrophic failure and fire hazard under the extreme circumstances of abnormal overvoltage conditions or varistor end-of-life.

It is specifically designed for Type 1 and Type 2 Surge Protective Devices (SPDs) used in markets and applications including:

  • Residential, Commercial, and Industrial buildings

  • Uninterruptable Power Supply (UPS)

  • Industrial motor control

  • Renewable energy

  • HVAC system

Benefits per a company press release include:

  • Facilitate meeting UL1449 listed Type 1 or Type 2 standards by incorporating 200 kA SCCR, 20 kA In, UL1449 Type 4 recognized component assembly.

  • Flexibility of using 50 kA and 75 kA Imax rated devices with the same footprint on PCB.

  • More options for designing remote indication/monitoring of SPD product or system via mechanically triggered AC and DC rated microswitch (Normally Open/Normally Closed, pin length, 2 pin/3 pin/without pin).

  • Clear LST working status indication via a visual tab option that notifies service technicians and maintenance engineers to replace LST at end-of-life (EOL) in order to continue optimal surge protection for the end-product.

  • Wide Operating Voltage Range: Up to 690 Vac for 50 kA version, up to 550 Vac for 75 kA version.

For more information, visit

Chad Cox. Production Editor, Embedded Computing Design, has responsibilities that include handling the news cycle, newsletters, social media, and advertising. Chad graduated from the University of Cincinnati with a B.A. in Cultural and Analytical Literature.

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