315 mA fast-blow fuse for secondary-side protection
The Littelfuse 0451.315NRL is a 315 mA fast-acting surface-mount fuse from the NANO²® 451 series, designed to clear quickly on high overcurrents — protecting downstream ICs, power modules, and control circuits from fault energy. Rated for 125 V AC and DC with a 50 A interrupting capacity, it safely opens the circuit under short-circuit conditions up to that fault level without casing rupture or arc propagation.
Breaking capacity and coordination data
The 50 A breaking capacity at 125 V AC/DC means this fuse can interrupt a fault current up to that level — sufficient for most secondary-side power supplies, DC-DC converters, and control circuits where the prospective short-circuit current stays below 50 A. Melting I²t of 0.0311 A²s is the energy required to melt the fusible element; this value is used to coordinate with upstream circuit breakers or fuses so that the 0451.315NRL opens before the upstream device on a downstream fault.
Temperature range and approvals
CSA and UL approvals mean the fuse is accepted for use in equipment certified to North American safety standards — a requirement for OEMs shipping into the US and Canadian markets.