Overcurrent protection for tight board spaces
The Littelfuse 1206L300SLWR is a polymeric PTC resettable fuse from the POLY-FUSE LoRho series, designed to protect low-voltage power rails in compact surface-mount designs. It holds 3 A continuously and trips within 4 seconds under fault conditions, resetting automatically once power is removed and the device cools. Rated for a maximum voltage of 6 V and a maximum fault current of 50 A, this part is suited for USB ports, battery packs, and handheld electronics where a short circuit could otherwise damage the upstream regulator or connector.
Low resistance keeps power loss minimal
Initial resistance is just 3 mOhms minimum, rising to 20 mOhms maximum after a trip event. The 1206 concave package (3.25 mm x 1.65 mm footprint, 1.00 mm max thickness) fits standard pick-and-place assembly and reflow profiles. Operating temperature range is -40°C to 85°C, covering most indoor and portable equipment environments. Safety approvals from cURus and TUV mean the part is accepted in equipment sold into North American and European markets without additional component-level certification.
Obsolete — sourcing through independent channels
Littelfuse has marked the 1206L300SLWR as Obsolete. The LoRho series is known for low internal resistance, so a replacement candidate should match the 3 A hold current, 6 V max rating, and 1206 footprint. Verify the initial resistance and post-trip resistance against the design's voltage-drop budget before substituting.