The LTC4058 is a complete constant-current/constant voltage linear charger for single cell lithium-ion batteries. Its DFN package and low external component count make the LTC4058 ideally suited for portable applications. Furthermore, the LTC4058 is designed to work within USB power specifications.The LTC4058 can Kelvin sense the battery terminal for more accurate float voltage charging. No external sense resistor or external blocking diode are required due to the internal MOSFET architecture. Thermal feedback regulates the charge current to limit the die temperature during high power operation or high ambient temperature conditions. The charge voltage is fixed at 4.2V and the charge current is programmed with a resistor. The LTC4058 terminates the charge cycle when the charge current drops to 10% of the programmed value after the final float voltage is reached.When the input supply (wall adapter or USB supply) is removed, the LTC4058 enters a low current state dropping the battery drain current to less than 2µA. Other features include charge current monitor, undervoltage lockout, automatic recharge and status pins to indicate charge termination and the presence of an input voltage.*US Patent 6,522,118ApplicationsCellular Telephones, PDAs, MP3 PlayersBluetooth Applications