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Littelfuse PolySwitch Resettable PPTC Fuses

Why we picked this?

Littelfuse PolySwitch and POLY-FUSE are Polymeric Positive Temperature Coefficient (PPTC) devices which offer a resettable overcurrent protection alternative, thereby reducing warranty, service and repair costs. Designed to limit unsafe currents while allowing constant safe current levels, resistance will "reset" automatically when the fault is removed and temperature returns to a safe levels.

Surface mount resettable PPTC devices provide overcurrent protection for applications where space is at a premium and resettable protection is desired.

Series we are focusing on:

The nanoSMD, miniSMD and SMD series are designed to provide overcurrent protection for applications where space is not a concern and resettable protection is preferred.

The RUEF and RXEF provide reliable, non-cycling protection against overcharging and short circuits events for rechargeable battery cells where resettable protection is favored.

Why use PPTCs?

Because they reset automatically. Many circuit designers choose PPTCs in instances where overcurrent events are expected to occur often, and where maintaining low warranty and service costs, constant system uptime, and user transparency are at a premium. If you’re thinking: why don’t I just use traditional fuses? Well, the clearest difference is that PPTCs are automatically resettable whereas traditional Fuses need to be replaced after they are tripped.

PPTC Characteristics and Terms:

Surface Mount Devices: (nanoSMDminiSMD and SMD)

  • A full range of compact footprints
  • Low hold current
  • Very fast trip time
  • Low resistance

Radial Leaded Series: (RUEF and RXEF)

  • Protection devices up to 600Vdc
  • A very high hold current
  • Low trip-to-hold current ratio
  • Low resistance

Welcome to Future Picks

Future Picks is a brand initiative dedicated to curating and showcasing best-selling and emerging products. Future aims to introduce our customers to the latest and most promising electronic components and solutions. We carefully select parts that reflect trends and complement each other.


Littelfuse - PTC - Group