Overcurrent protection for 2 A rails
The Littelfuse 0451002.NRL is a 2 A fast-blow surface-mount fuse from the NANO²® 451 series, rated for 125 V AC and DC circuits. With a breaking capacity of 50 A at rated voltage, it safely clears fault currents up to that level without rupturing the package — critical for secondary-side protection in power supplies and DC-DC converter outputs where the available fault current stays below 50 A.
Melting I²t and inrush coordination
The melting I²t of 0.53 is the energy required to open the fuse element. For a capacitive input stage drawing a 10 A peak inrush for 1 ms, the I²t is 0.1 — well below the fuse's let-through, so the fuse holds during start-up. Use this figure to coordinate with downstream semiconductor surge ratings and to ensure selectivity with upstream branch protection. DC cold resistance of 0.0367 ohms means the fuse adds about 74 mV of voltage drop at rated current — negligible in a 5 V or 12 V rail, but worth accounting for in low-voltage, high-current paths where every millivolt matters for load regulation.
Temperature range and board integration
Approved by CSA, PSE, and UL — the fuse carries acceptance for North American and Japanese markets without additional agency testing. The UL listing covers the 125 V AC/DC rating; the PSE mark is required for equipment sold in Japan.