The LTC4053 is a standalone linear charger for lithiumion batteries that can be powered directly from a USB port. The IC contains an on-chip power MOSFET and eliminates the need for an external sense resistor and blocking diode. Thermal regulation automatically adjusts charge current to limit die temperature during high power or high ambient temperature conditions. This feature protects the end product and the LTC4053 from thermal stress while the IC charges the battery at maximum rate without interruption.