Device identity and board-fit parametrics
The Littelfuse 1206L025YR is a polymeric PTC resettable fuse from the POLY-FUSE 1206L series, surface-mounted in a 1206 (3216 Metric) concave package. It is rated for a hold current of 250 mA at 16 V maximum, with a maximum interrupt rating of 100 A. The 80 ms typical time-to-trip means this device clears a fault fast enough to protect most low-power signal and power rails, but the trip characteristic is slower than a traditional one-shot fuse — design the downstream circuitry to survive the full I²t let-through during the trip interval.
Resistance states and derating
Initial cold resistance is a minimum 550 mOhms; after tripping and cooling, the post-trip resistance rises to a maximum of 2.3 Ohms. The ratio between these two states (about 4:1) means the circuit sees a higher series resistance after a fault event — the load current settles lower than the original hold value until the PTC fully resets. Derate the hold current above 25°C per the POLY-FUSE family curve; at 85°C ambient the effective hold current drops to roughly 50% of the 25°C rating.
Lifecycle and compliance standing
It is qualified with cURus and TUV agency approvals, which covers the safety certification requirements for most North American and European equipment designs.