High-power varistors work at 125°C with 2.5 kV isolation voltage

Littelfuse, Inc., the global leader in circuit protection, today introduced its first varistor series designed for high power applications that can operate at ambient temperatures up to 125°C with 2500V isolation voltage. The HMOV™ Varistor Series’ high operating temperature is 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. The new products were announced at the company’s booth (Hall A6-Booth 153) during Electronica, the international trade fair for electronic components, systems. and applications, held November 8-11, 2016, at the Munich Trade Fair Center.

The HMOV™ Varistor Series’ 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 stress test, and high isolation voltage (2500V) make the HMOV™ Varistor Series the highest performance radial-leaded varistor series currently on the market. The series is available in disc diameters of 10mm, 14mm and 20mm.

The HMOV™ Varistor Series is best-suited for high temperature and high power DC or AC applications including:

• industrial automation controls,
• solar power inverters,
• security systems,
• fire alarm and smoke detectors,
• smart meters,
• outdoor LED lighting,
• base transceiver station (BTS) power supplies, and
• harsh environment/outdoor power supplies.

“The HMOV™ Varistor Series combines the ability to operate at ambient temperatures up to 125°C with superior surge current handling capability,” said Johnny Chang, Littelfuse product manager for the HMOV™ Series Varistor line. “That allows it to provide the safest, most reliable, energy-efficient and cost-saving circuit protection solution available for DC and AC applications that require higher power in extremely hot indoor and outdoor environments.”  

The HMOV™ Varistor Series offers these key benefits:

• High operating temperature of 125ºC allows the high power end products into which it’s built to run safely at higher ambient temperatures and saves costs by eliminating the need for an additional heat sink or potting process.
• High isolation voltage (2500V) eliminates the need for additional insulation material and helps minimize PCB size by reducing the space required between the varistor and other components on the board.
• Thermal shock testing (1000 cycles from -55ºC to +125ºC) offers enhanced reliability that can extend the lifetime of the end products.
• Meets UL 1449 and IEC 60950-1, which supports worldwide compliance for end products.