375 mA fast-blow for sensitive board-level protection
The Littelfuse 0451.375MRSN is a 375 mA, 125 V AC fast-blow surface-mount fuse from the NANO²® 451 series. Its 50 A interrupting rating at rated voltage means it can safely clear a fault up to that current without rupturing the package — critical for protecting downstream silicon in a power supply or control circuit.
Melting I²t and cold resistance for coordination
With a melting I²t of 0.0425, this fuse coordinates with semiconductor junctions and PCB traces that have a lower I²t withstand — the fuse opens before the downstream component exceeds its thermal limit. The 0.61 Ω DC cold resistance means the voltage drop at rated current is about 229 mV, negligible in a 125 V circuit but worth checking in a low-voltage rail. The fast-blow response time suits circuits with inrush-sensitive loads such as relays, solenoids, or capacitive inputs where a time-delay fuse would pass the surge but a fast-blow clears before damage occurs.
Surface-mount package and environmental range
CSA and UR approval agency marks confirm acceptance for North American and Canadian equipment — a requirement for UL 508A industrial control panels and similar listings.