750 mA protection for 125 V rails
The Littelfuse 0451.750NRL is a 750 mA fast-blow fuse from the NANO² 451 series, rated for 125 VAC and 125 VDC circuits. With a 50 A breaking capacity at rated voltage, it safely interrupts overcurrents up to that level without rupturing the package — critical for clearing hard shorts on a 125 V bus without cascading to upstream protection.
Fast-blow response and surge tolerance
The fast-blow characteristic means the fuse element opens quickly on sustained overloads, protecting downstream semiconductors and thin traces from thermal damage. The melting I²t of 0.185 quantifies the energy needed to melt the element — useful for sizing the fuse against inrush currents from capacitive loads or motor starts without nuisance opening. DC cold resistance measures 0.245 Ohms, which at 750 mA produces a voltage drop of roughly 184 mV — negligible for most 125 V circuits but worth factoring into low-voltage sense paths.
Surface-mount footprint and thermal environment
Housed in a 2-SMD square end block package measuring 6.10 mm x 2.69 mm x 2.69 mm, the 0451.750NRL mounts directly to a PCB pad pattern. The surface-mount format suits automated pick-and-place assembly; the square end block provides stable solder joints under vibration.