SE9017 is a complete constant-current & constant voltage linear charger for single cell ithium-ion and Lithium-Polymer batteries.  Its SOT-23 package and low external component count make SE9017 ideally suited for portable applications.  Furthermore, the SE9017 is specifically designed to work within USB power specification.   At the same time, SE9017 can also be used in the standalone lithium-ion and Lithium-polymer battery chargers. No external sense resistor is needed, and no blocking diode is required due to the internal MOSFETarchitecture.  Thermal feedback regulates the charge current to limit the die temperature during high power operation or high ambient temperature.   The charge voltage is fixed at 4.2V, and the charge current can be programmed externally with a single resistor.  The SE9017 automatically terminates the charge cycle when the charge current drops to 1/10th the programmed value after the final float voltage is reached.   When the input supply (wall adapter or USB supply) is removed, the SE9017 automatically enters a low current stage, dropping the battery drain current to less than 2uA.   The SE9017 can be put into shutdown mode, reducing the supply current to 20uA.