The 1206L110/12WR is a Littelfuse POLY-FUSE® polymeric PTC resettable fuse in the 1206L series, rated for a 1.1 A hold current (Ih) at 12 V max. This means the device will not trip below 1.1 A of continuous current at 25 °C ambient, so it sits in the circuit as a low-resistance element — 40 mOhms typical initial resistance — until a fault drives the current above the 2.2 A trip threshold (It). Once tripped, the polymer PTC element heats up and its resistance jumps to a maximum of 210 mOhms post-trip (R1), limiting the fault current to a safe level. The device resets automatically when power is removed and the polymer cools, making it a resettable alternative to a one-time fuse for overcurrent protection on low-voltage DC rails.
Package and rework reality
The concave body means the terminations wrap under the ends — rework is straightforward with hot air; the part lifts cleanly at 260 °C with a gentle twist, and the pad layout is standard 1206.
Fault handling and safety approvals
Rated to interrupt fault currents up to 100 A max at 12 V, with a typical time to trip of 100 ms at 8 A. This fast trip response protects downstream components from short-circuit events on 5 V or 12 V power buses, USB ports, or battery lines.