5 A fast-blow fuse for 125 V rails — NANO² 451 series
The Littelfuse 0451005.NR is a 5 A fast-blow surface-mount fuse from the NANO² 451 series, rated for 125 V AC and DC circuits with a 50 A interrupting capacity at rated voltage. The 0.0125 Ohm cold resistance and 5.566 melting I²t figure let you coordinate the fuse with downstream components — the I²t tells you the energy let-through before the element opens, which matters for protecting semiconductor loads like rectifiers or DC-DC converters on the same rail.
Surface-mount footprint and regulatory acceptance
The 2-SMD square end block package (6.10 mm x 2.69 mm x 2.69 mm) suits reflow assembly on standard PCB pads — the body is the same width as the terminal pads, so the solder fillet wets the full end face. Approved by CSA, PSE, and UL — the fuse carries acceptance for North American and Japanese regulatory frameworks, which simplifies certification of the end equipment.