The LTC4075/LTC4075X are standalone linear chargers that are capable of charging a single-cell Li-Ion battery from both wall adapter and USB inputs. The chargers can detect power at the inputs and automatically select the appropriate power source for charging. No external sense resistor or blocking diode is required for charging due to the internal MOSFET architecture. Internal thermal feedback regulates the battery charge current to maintain a constant die temperature during high power operation or high ambient temperature conditions. The float voltage is fixed at 4.2V and the charge current is programmed with an external resistor. The LTC4075 terminates the charge cycle when the charge current drops below the programmed termination threshold after the final float voltage is reached. With power applied to both inputs, the LTC4075/LTC4075X can be put into shutdown mode reducing the DCIN supply current to 20A, the USBIN supply current to 10A, and the battery drain current to less than 2A.