Hold current and trip threshold
The 1206L020YR is a polymeric PTC resettable fuse from Littelfuse's POLY-FUSE 1206L series. It holds 200 mA continuously without tripping — below that current the resistance stays low, under 650 mOhms initial. Once the load exceeds 420 mA trip current, the PTC heats up and its resistance jumps to a maximum of 2.6 ohms post-trip, limiting the fault current. The trip happens in 100 ms typical at 25°C — fast enough to protect a USB port or a low-voltage DC rail from a sustained overcurrent or short. The part resets automatically when power is removed and the PTC cools, so no fuse replacement is needed after a fault clears.
Fault current and voltage ceiling
Rated for a maximum fault current of 100 A at 24 V — the PTC can interrupt a hard short up to that level without rupturing. The 24 V max voltage limits it to low-voltage DC circuits: USB 5 V, 12 V automotive auxiliary, or 24 V industrial sensor rails. Do not use on 48 V or mains AC without a series current-limiting element. The 1206 footprint (3.20 mm x 1.65 mm, concave termination) is standard for reflow assembly.
Automotive qualification and approvals
AEC-Q200 qualified — this PTC meets the passive-component stress test sequence for automotive electronics: temperature cycling, moisture resistance, mechanical shock, and solder heat.
Production status and sourcing
Littelfuse lists the 1206L020YR as Active — no discontinuation notice or last-time-buy window has been issued.