375 mA fast-blow SMD fuse for secondary-side protection
The Littelfuse 0451.375NRL is a 375 mA fast-blow SMD fuse from the NANO²® 451 series, rated for 125 V AC and 125 V DC with a breaking capacity of 50 A at rated voltage. The 0.0425 melting I²t and 0.61 Ohms cold resistance give a predictable clearing profile for overcurrent events on a PCB. This is a board-mount fuse in a 2-SMD square end block package measuring 6.10 mm x 2.69 mm x 2.69 mm, surface-mount only. The fast-blow response means it opens quickly on high-fault currents, suited for protecting sensitive downstream silicon where a slow-blow would let through too much energy.
Breaking capacity and approvals
Rated 50 A breaking capacity at 125 V AC/DC — this fuse safely interrupts fault currents up to 50 A without rupturing. For a 375 mA rated fuse, that is over 130× the nominal current, covering most secondary-side fault scenarios in telecom, industrial control, and power-supply outputs. The 0451.375NRL carries CSA and UL approvals, meaning it is accepted for use in equipment sold into North American and Canadian markets without additional agency review of the fuse itself.