3 A fast-blow SMD fuse for 125 VDC rail protection
The Littelfuse 0451003.NRL is a 3 A, 125 VAC/125 VDC fast-blow fuse in the NANO²® 451 series, designed for surface-mount board-level overcurrent protection where a small footprint and automated assembly are required. Rated for 50 A breaking capacity at 125 V, this fuse is suited for secondary-side protection in DC-DC converter outputs, point-of-load regulators, and telecom line cards — not for primary panel-level fault interruption where higher interrupt ratings are needed. The fast-blow response time means it clears quickly on overcurrent events, making it a good match for protecting sensitive semiconductor loads like ASICs, FPGAs, and memory banks that cannot tolerate sustained fault current.
Melting I²t and DC resistance for coordination
With a melting I²t of 1.65 A²s, this fuse can withstand brief inrush currents from capacitive loads — a 100 µF input capacitor charging from 125 VDC produces an inrush energy well below this threshold, so nuisance blowing is unlikely.
SMD package and assembly fit
Housed in a 2-SMD, square end block package measuring 6.10 mm x 2.69 mm x 2.69 mm, the 0451003.NRL fits standard pick-and-place equipment and reflow soldering profiles — no manual handling required. Available in Tape & Reel (TR) for volume production or Cut Tape (CT) for prototype and low-volume builds — the reel quantity supports automated assembly without reel changeovers for moderate batch sizes.
Regulatory approvals and compliance
The 0451003.NRL carries CSA, PSE, and UL approvals — accepted in North American and Japanese markets without additional agency review for most equipment-level safety certifications.