2 A fast-blow SMD fuse for secondary-side protection
The Littelfuse 0451002.MRL is a 2 A fast-blow surface-mount fuse from the NANO²® 451 series, designed for board-level overcurrent protection where space is constrained and a quick open on fault is required. Rated for 125 V AC and 125 V DC circuits, it fits secondary-side power rails, DC-DC converter inputs, and low-voltage DC bus protection in telecom, industrial control, and consumer electronics.
Fast-blow response and inrush withstand
The fast-blow response clears the fuse quickly on a sustained overcurrent, but the 0.53 melting I²t gives it enough energy tolerance to ride through capacitor-charging inrush or brief current spikes without nuisance opening. A 50 A breaking capacity at rated voltage means the fuse can safely interrupt a fault current up to that level without rupturing or sustaining an arc — sufficient for most secondary-side supplies where the upstream source impedance limits fault current.
Surface-mount package and thermal range
Housed in a 2-SMD square end block measuring 6.10 mm x 2.69 mm x 2.69 mm, the 0451002.MRL is pick-and-place compatible and suits high-density PCB layouts where a through-hole cartridge fuse would not fit.
Regulatory acceptance and sourcing posture
Approved by CSA, PSE, and UL — the fuse carries the certifications needed for equipment sold into North American and Japanese markets without additional agency review.