PolySwitch Surface Mount Resettable PTCs Littelfuse PolySwitch Surface-Mount (SMD) Resettable PTCs provide overcurrent protection for applications where space is at a premium, and resettable protection is desired. The components are reliable and capable of protecting computer and consumer electronics against temporary overcurrent faults. Package size varies from 0402 to 3425, while the current hold ranges from 50mA to 7.0A. The Littelfuse PolySwitch SMD product family is qualified to strict automotive standards (following the AECQ200 specification). As a result, these PTCs are suitable for protecting Electronic Control Units (ECUs) against damage from faults that would otherwise require costly, complete module replacement.