What the 3.15 A rating and 50 A breaking capacity mean for your board
The 04513.15MRL is a Littelfuse NANO²® 451 series surface-mount fuse rated 3.15 A at 125 V AC or DC. The 50 A interrupting rating at 125 V means it can safely clear a fault up to that current without rupturing the package — critical for secondary-side protection in power supplies where the available fault current from the bulk capacitor bank can exceed the fuse's own rating if undersized. Fast-blow response and a melting I²t of 1.92 mean this fuse opens quickly on high overcurrents but tolerates brief inrush pulses — a fit for circuits where the load's startup surge is short relative to the fault energy.
Package, footprint, and temperature range
Housed in a 2-SMD square end block measuring 6.10 mm x 2.69 mm x 2.69 mm, the 04513.15MRL occupies the same footprint as other NANO² 451 fuses — the pad layout is shared across the current ratings in the series, so a single PCB pattern serves multiple BOM variants. Surface-mount construction suits reflow assembly.
Approvals and compliance
Carries CSA, PSE, and UL recognition — the UL listing covers the 125 V AC/DC rating and 50 A interrupting capacity, which is the standard a safety engineer needs for a secondary-side fuse in equipment sold into North America.