The LTC4097 is a standalone linear battery charger that is capable of charging a single-cell Li-Ion or Li-Polymer battery from both wall adapter and USB inputs. The charger 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 LTC4097 terminates the charge cycle when the charge current drops below the user programmed termination threshold after the final float voltage is reached. The LTC4097 can be put into shutdown mode reducing the DCIN supply current to 20µA, the USBIN supply current to 10µA, and the battery drain current to less than 2µA even with power applied to both inputs.Other features include trickle charge, automatic recharge, undervoltage lockout, charge status output, an NTC thermistor input used to monitor battery temperature and VNTC power present output with 120mA drive capability.ApplicationsCellular TelephonesMP3 PlayersPortable Handheld Devices