What the 160 mA rating means on a board-level fault
The 0451.160MRSN is a Littelfuse NANO²® 451 series surface-mount fuse rated 160 mA at 125 VAC, with a fast-blow response time. At that current, the 50 A breaking capacity at rated voltage means it can safely interrupt a short-circuit fault up to 50 A without the fuse body rupturing or arcing across the SMD pads — critical for secondary-side protection on a control transformer or a DC rail feeding sensitive logic. The melting I²t of 0.0048 A²s tells you how much energy the fuse absorbs before opening. For a 160 mA rail, a downstream capacitor bank charging inrush that exceeds this I²t will nuisance-blow the fuse on power-up — so if the board has a bulk cap over a few hundred microfarads, you may need a slow-blow variant in the same footprint. The DC cold resistance of 1.2157 Ω at room temperature means the fuse drops about 190 mV at rated current — negligible for a 5 V or 12 V rail, but worth checking if the load is a 3.3 V sensor drawing close to the fuse rating.
Housed in a 2-SMD square end block package measuring 6.10 mm x 2.69 mm x 2.69 mm, the 0451.160MRSN sits flush on the PCB with no through-hole leads. The square end terminations are the same width as the body, so the solder pad footprint is straightforward — no special stencil aperture needed for a standard reflow profile. The cold resistance quoted at room temperature shifts with temperature, but the fuse element's opening characteristic stays within the fast-blow band across the full range. Supplied on Tape & Reel (TR) — pick-and-place ready for volume assembly. The reel quantity is standard for the NANO² 451 series; confirm the reel count with your distributor at quote time.
Approvals and compliance
Carries CSA and UR approval agency marks — accepted for North American equipment listings.