Obsolete — sourcing path for a 3 A 1206 fuse
The Littelfuse 1206SFP300F/32-2 is officially obsolete per the manufacturer's product status. The fuse is rated 3 A continuous at 32 V DC with a breaking capacity of 50 A at rated voltage. That 50 A interrupt rating is the key fit criterion: it must exceed the prospective short-circuit current available at the fuse location in the circuit. In a 32 V DC rail with a stiff battery or bulk capacitor bank, the available fault current can easily exceed 50 A — verify the supply impedance before committing this part to a new design.
1206 footprint and thermal integration
Housed in the standard 1206 (3216 metric) chip package for surface-mount reflow assembly. The 0.035 Ohm cold resistance generates I²R heat at rated current — 3 A squared times 0.035 Ohm is about 0.315 W. On a standard FR-4 board with 1 oz copper pads, that self-heating keeps the fuse element well below its opening temperature in still air. Melting I²t is 1.35 A²s. This is the energy required to clear the fuse element. For inrush or pulse currents, the I²t of the pulse must stay below the fuse's melting I²t with a derating factor (typically 20-30% margin). A 3 A fast-blow fuse with a 1.35 I²t rating will tolerate brief surges — a 10 A pulse for 10 ms delivers 1.0 A²s, which is within the margin. UL approval covers the safety certification for North American equipment.