The RT9055-SSWSC is a single cell linear Li-Ion battery charger IC from Richtek Technology. The IC contains a DC/DC converter that provides an adjustable voltage output and is designed to charge 3.6V and 4.2V single cell Li-Ion batteries with an external power source. It uses Richtek's proprietary SafeSwap Technology, which is specially designed to prevent incorrect insertion of batteries, preventing short-circuits and battery damage. The charger provides constant current/constant voltage charging and offers over-charge, over-discharge, over-temperature and short-circuit protection. The IC features a synchronous rectifier with a 95% efficiency rating, allowing for power saving operation. The RT9055-SSWSC also offers a low-voltage and battery detect pin, which enables the system to determine when the battery needs to be charged or replaced.