What is a Micro Fuse? A micro fuse is a radial leaded subminiature fuse offered in either a cylindrical or rectangular form factor. Micro fuses were originally designed for the U.S. Space Program. The micro fuse is made with either glass, plastic or metal bodies. They are designed to be electrically equivalent to miniature glass cartridge fuses in a smaller package with higher tolerance to impact and vibration. Micro fuses can plug in to a PC board mounted fuse holder. Micro fuse voltage ratings typically range from 65 volts AC to 300 volts AC. Micro fuses with voltage ratings up to 450 volts DC are also available. Micro fuses are offered in fast acting or time lag versions. Micro fuses are typically built in accordance with UL 248-14 and CSA C22.2/No.248.14 or IEC 60127-3 standards. Some fuse micro series are also offered in MIL Spec versions. The fuse micro IEC 60127-3 series is offered in several versions:

IEC Designation	Opening Speed	Breaking Capacity	Voltage Rating	Leads
IEC 127-3, Sheet I	Quick Acting	Low	125V	Radial
IEC 127-3, Sheet II	Quick Acting	Low	125V	Axial
IEC 127-3, Sheet III	Quick Acting	Low	250V	Radial/Axial
IEC 127-3, Sheet IV	Time Lag	Low	250V	Radial/Axial

Littelfuse and Bussmann offer micro fuses. Littelfuse micro fuse brand names include TR5®, TR3 ®, TE5 ® and TE3 ®. The Bussmann micro fuse brand name is PC-Tron ®.

Our micro fuse selection can be found by browsing our data sheet finder.
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An Assortment of Micro Fuses