Resettable overcurrent protection for 125 mA rails
The Littelfuse 1206L012WR is a polymeric PTC resettable fuse from the POLY-FUSE® 1206L series, designed to protect low-current DC power rails against overcurrent faults. Its 125 mA hold current (Ih) defines the maximum steady-state current the device passes without tripping; once the fault current exceeds the 290 mA trip current (It), the PTC element heats up and its resistance jumps from a typical 1.5 Ω initial resistance (Ri) to a maximum 6 Ω post-trip resistance (R1), limiting the fault current within 200 ms (time to trip). After the fault clears and power is removed, the device cools and resets to its low-resistance state — no fuse replacement needed. Rated for a maximum voltage of 30 V and capable of interrupting fault currents up to 100 A, this PTC suits secondary-side protection in DC-DC converters, USB ports, battery management, and other 5 V to 24 V circuits where a resettable overcurrent device is preferred over a one-time fuse.
Package, approvals, and operating range
The device carries cURus and TUV approvals, confirming compliance with North American and European safety standards for overcurrent protection components.
Active production and sourcing posture
The 1206L012WR is listed as Active on the manufacturer's lifecycle record, meaning Littelfuse continues to manufacture the part with no announced end-of-life.