Obsolete — sourcing through independent channels
Littelfuse has marked the 0451.375MR as obsolete, meaning the manufacturer no longer produces it as a standard catalog item.
Key ratings for board-level protection
Rated 375 mA at 125 V AC or DC, this fast-blow fuse clears overcurrents quickly — the 0.0425 melting I²t means it opens fast enough to protect downstream silicon from short-duration fault energy. Breaking capacity is 50 A at the rated voltage — sufficient for most low-power secondary-side circuits; the fuse interrupts a fault without rupturing or sustaining an arc. The 0.61 Ohm cold resistance helps predict voltage drop at rated current — about 230 mV across the fuse at 375 mA, which matters for low-voltage rails.
Housed in a 2-SMD square end block package measuring 6.10 mm x 2.69 mm x 2.69 mm, it sits flat on the pad with no tombstoning risk — the end-cap terminations are symmetrical. Surface-mount on a standard 2-SMD footprint; the Tape & Reel packaging feeds directly into a pick-and-place machine for high-volume assembly.