750 mA fast-blow fuse for secondary-side overcurrent protection
The 0451.750NR is a 750 mA fast-blow surface-mount fuse from the Littelfuse NANO² 451 series, designed for board-level overcurrent protection on 125 VAC or 125 VDC rails. Its 50 A breaking capacity at rated voltage means it safely interrupts fault currents up to that level without rupturing — adequate for secondary-side power supplies and control circuits where the available fault current stays below 50 A. The 0.185 melting I²t gives the energy needed to clear the element; a downstream semiconductor rated for less I²t withstand will fail before the fuse opens unless coordinated.
Obsolete — sourced through independent channels
For new designs, consider a current-production NANO² 451 variant with the same package footprint and voltage rating, but verify the I²t and breaking capacity against the BOM requirement.
Surface-mount footprint and environmental range
Housed in a 2-SMD square end block package measuring 6.10 mm x 2.69 mm x 2.69 mm, the fuse sits flat on the PCB with end-cap terminations — no through-hole leads, so the layout uses standard SMD pads with no drilled holes.
CSA and UL approvals for North American markets
The fuse carries CSA and UL approval agency marks — accepted in equipment destined for North American regulatory review without additional fuse testing.