SFF 2 A fast-blow — what the ratings mean for the board
The 0603SFF200FM/32-2 is a Littelfuse SFF series fast-blow fuse in the 0603 (1608 metric) surface-mount package, rated 2 A continuous at 32 V DC. The 35 A breaking capacity at rated voltage means it can safely interrupt a fault current up to that level without sustaining an arc — the fuse opens before the downstream trace vaporises. The 0.06 I²t melting integral tells you the energy let-through during a short is low enough to protect a 2 A-rated trace or component in a secondary-side DC rail. Cold resistance is 0.044 Ohms, so at 2 A the self-heat is under 0.2 W — negligible in free air, but in a dense 0603 layout the adjacent parts see that thermal rise.