15 A fast-blow in a 2-SMD square end block
The 0451015.MRSN is a Littelfuse NANO²® 451 series surface-mount fuse rated 15 A continuous with a fast-blow response time — it opens within milliseconds on a moderate overcurrent, protecting downstream silicon before the fault energy climbs. The 2-SMD square end block package (6.10 mm x 2.69 mm x 2.69 mm) fits standard pick-and-place and reflow profiles, so it flows through the same line as the rest of the board.
Breaking capacity and coordination
Breaking capacity is 100 A AC and 150 A DC at the rated 65 V — that means the fuse can safely interrupt a fault current up to those levels without rupturing or arcing across the element. The melting I²t of 97.82 is the energy let-through before the fuse opens; use it to coordinate with upstream breakers and downstream semiconductor surge ratings so the fuse clears before the board traces vaporize. DC cold resistance is 0.0037 ohms — at 15 A the resistive power loss is under a watt, so the fuse stays cool in normal operation and the voltage drop across it is negligible for a 65 V rail.