The LTC4068 is a complete constant-current/constantvoltage linear charger for single cell lithium-ion batteries. Its DFN package and low external component count make the LTC4068 ideally suited for portable applications. Furthermore, the LTC4068 is designed to work within USB power specifications.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 LTC4068 terminates the charge cycle when the charge current drops below the programmed termination threshold after the final float voltage is reached.When the input supply (wall adapter or USB supply) is removed, the LTC4068 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 adequate input voltage.Protected by U.S. Patents, including 6522118.ApplicationsCellular Telephones, PDAs, MP3 PlayersBluetooth Applications