Active production — what it means for your BOM line
The 0451.500NRL: This is a 500 mA fast-blow fuse in the NANO²® 451 series, rated for 125 V on both AC and DC circuits.
Breaking capacity and I²t — the real protection envelope
Rated breaking capacity is 50 A at the rated voltage — meaning the fuse can safely interrupt a fault current up to 50 A without rupturing or sustaining an arc. For a 500 mA rail, that is 100× the load current, giving solid margin against a dead short. Melting I²t is 0.0795 A²s — this is the energy needed to clear the fuse element. In a circuit with inrush, the I²t of the surge must stay below this value to avoid nuisance opens. A 500 mA fast-blow with this I²t handles moderate capacitive inrush on a small DC-DC input or a low-power sensor node. The operating temperature range spans -55°C to 125°C, so it works in an engine-bay ECU or a cold-chain logger without derating the current at the extremes.
Package and board-fit for hand-assembly
Housed in a 2-SMD square end block package measuring 6.10 mm x 2.69 mm x 2.69 mm — the end-cap terminations are large enough for hand-soldering with a fine tip, and the square body sits flat on the pad without tombstoning during reflow.
Approvals and compliance for global shipping
Listed with CSA and UL approvals — the fuse is accepted in North American and Canadian equipment without a separate agency review. The NANO²® 451 series is a board-mount fuse (cartridge style excluded), so it is designed for direct soldering onto a PCB rather than a panel-mount holder.