New Industry Products

Littelfuse Introduces New Products Aimed at Surge Protection

February 21, 2022 by Gary Elinoff

The new series provide circuit protection against overcurrent and potentially catastrophic high-voltage transients.

Littelfuse, a global manufacturer specializing in all phases of circuit protection, power control, and sensing, has introduced two new lines of surge-protection components.

The first is the 607 series of compact cartridge fuses, which are specced for 500 VAC/VDC and can handle up to 63 A. The second is Littelfuse's Xtreme Varistor series, rated at up to 680 VAC, which will protect vulnerable circuitry against multiple transitory high-voltage surges.


The 607 Series

Members of the compact 607 series measure 10 mm x 32 mm, saving significant board space over competing designs. These high-current, high-voltage cartridge fuses are able to handle 500 V, AC or DC, and are capable of operating at a wide temperature range of -55 to +125 ℃.


The compact 607 series cartridge fuses. Image used courtesy of Littelfuse


As shown above, the fuses, in addition to their small size, offer end caps with integrated stand off leads. This eliminates the need for mounting accessories or lead-forming processes, saving cost. 

Coded 040, 050 and 063, the fuses are rated for an amperage of 40, 50 and 63 A, respectively. Their interrupt rating, or breaking capacity — the maximum current that a fuse can safely handle in the instant before it breaks electrical contact — is included in the table below, along with a number of additional key specifications.


607 Series Specifications
Part Number Amerpage Rating (A) Interrupt Rating DC Resistance (mΩ) Melting Point (I2 x s)
0607040 40

10 KA @ 500 VDC
 10 KA @ 500 VAC 

1.87 2570
0607050 50 1.45 4230
0607063 63

10 KA @ 500 VDC 
5 KA @ 500 VAC 
10 KA @ 300 VAC 

1.02 7060


Applications for the 607 Series

The fuses, which are RoHS-compliant, UL-approved, and free of halogens and toxic lead, are intended for a number of applications. These include:

  • EV Charging 
  • HVAC systems 
  • Uninterruptible Power Supply (UPS) 
  • Inverters and rectifiers 
  • Data centers
  • Telecom 

Littelfuse’s Xtreme Varistor Series

Littelfuse’s Xtreme Varistor series of metal oxide varistors (MOVs) can be seen as a complement to the 607 series. While the latter protects against overcurrent, the Xtreme Varistor series guards against the sudden, unexpected high-voltage surges that can damage or destroy sensitive electronic equipment.

Varistors’ resistance, normally high, is immediately and dramatically reduced in response to dangerously high voltage spikes. In effect, this “clamps down” on the spike before it can do damage. 

Littelfuse’s new devices, constructed with the company’s proprietary powder formulation, will provide protection against multiple high-surge energy and high-current pulses without degradation.


Members of Littel’s Xtreme Varistor series. Image used courtesy of Littelfuse


The Xtreme Varistor family can operate in the presence of constant, non-surge voltages of up to 680 VRMS or 895 VDC. The units can operate at temperatures of up to 125 ℃, and are available in six sizes: 5, 7, 10, 11, 14, and 20 mm. 


Safety and Environmental Standards

Since members of the Xtreme Varistor series are designed to deal with hazards related to safety, they are rated to many international standards, not all of which are listed below:

  • Meets the UL94 flammability V-0 rating
  • UL 1449
  • CSA C22.2 No. 269-5
  • RoHS compliant, Halogen-free, and Pb-free


  • Home and building automation
  • Large and small appliances
  • Outdoor LED lighting
  • Fire alarms and smoke detectors
  • Smart metering
  • Ground fault and arc fault circuit interrupters
  • USB outlets


Feature image used courtesy of Hutton Power & Light, LLC