HMOV™ Varistor working at 125°C

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Littelfuse introduced the first varistor series designed to operate at temperatures Up to 125°C with 2500V Isolation Voltage. Their new silicone coating technology makes high temperature and high isolation voltage operation possible.


The HMOV™ Varistor Series from Littelfuse can operate at ambient temperatures up to 125°C with 2500V isolation voltage, an advance made possible through the use of a new silicone coating technology.
Competitive epoxy-coated varistor designs are typically limited to maximum temperatures of just 85°C while similar phenolic coating designs have limited isolation voltages. This high operating temperature makes it possible to reduce end-product production costs by eliminating the need for an additional heat sink or potting process.
The combination of high operating temperature, high surge current absorption of up to 10kA (8/20µs), reliability confirmed by a 1000-cycle thermal shock test, and high (2500V) isolation voltage make it the highest performance radial-leaded varistor currently on the market.


Features Benefits

High isolation voltage of 2500V

Eliminates the need for an additional heat sink or potting process used to dissipate heat

Thermal shock tested from -55ºC to +125ºC, 1000 cycles

Ideally suited for use in higher ambient temperature applications

High operating temperature of 125°C

Eliminates the need for the additional insulation material

Meets UL 1449 and IEC 60950-1

Minimize PCB size by reducing space required between the varistor and other components

Offers enhanced reliability that can extend the lifetime of the end product

Enables end product worldwide compliance


  • Industrial automation controls
  • Solar power inverters
  • Security systems
  • Fire alarm and Smoke detectors
  • Smart meters
  • LED lighting base transceiver station (BTS) power supplies
  • Harsh environment/outdoor power supplies