What this 1.6 A fast-blow fuse does on the board
The 045101.6NRL is a Littelfuse NANO²® 451 series surface-mount fuse rated 1.6 A at 125 VAC and 125 VDC with a fast-blow response time. It comes in a 2-SMD square end block package measuring 6.10 mm x 2.69 mm x 2.69 mm, supplied on Tape & Reel for pick-and-place assembly. The 50 A breaking capacity at rated voltage means it can safely interrupt a fault current up to that level without rupturing or sustaining an arc — critical for protecting downstream traces and components in a 125 V rail.
Breaking capacity and I²t — the numbers that matter for protection
With a melting I²t of 1.06 A²s and a DC cold resistance of 0.058 Ohms, this fuse opens fast on a hard short — the I²t value tells you the energy let-through before the element clears, which is the figure the PCB trace width calculation and the downstream semiconductor surge rating need to see. The 50 A interrupting rating at 125 VAC/VDC is the same for both AC and DC circuits — unusual for a small SMD fuse, where DC breaking is often derated. That dual-voltage spec simplifies BOM planning for boards that see both a 125 VAC mains-derived rail and a 125 VDC battery bus.
Approvals and compliance for global equipment
The 045101.6NRL carries CSA, PSE, and UL approvals — covering North American and Japanese regulatory acceptance. For a power supply or telecom board shipping into those markets, this fuse meets the safety agency listing requirements without a separate component qualification. Operating temperature range is -55°C to 125°C, which covers both commercial and industrial ambient conditions — the fuse does not derate significantly across the band, so the 1.6 A rating holds in a hot enclosure near a power stage.