The 0451.500NR: No official successor order code is recorded from Littelfuse for this specific line. A board-spin or a parametric substitute evaluation is the practical next step for new builds.
What the ratings mean for fit
Rated 500 mA at 125 V AC or DC — this fuse clears a sustained overcurrent above the 500 mA threshold in a fast-blow response, meaning it opens quickly on a fault but may nuisance-blow on a brief inrush that exceeds the melting I²t of 0.0795. Breaking capacity is 50 A at the rated voltage — the fuse can safely interrupt a fault current up to 50 A without rupturing the case. That ceiling is low compared to modern SMD fuses; verify the prospective short-circuit current at the fuse position stays under 50 A.
2-SMD square end block package measuring 6.10 mm x 2.69 mm x 2.69 mm — the footprint is the same as the standard NANO² 451 series.
Approvals and compliance
CSA and UL approved — the fuse carries acceptance for North American and Canadian regulatory jurisdictions.