ME4054 is a constant-current/constant-voltage linear charger for single cell lithium-ion batteries. Its Thin SOT package and low external component count make the ME4054 ideally suited for portable applications. Furthermore, the ME4054 is specifically designed to work within USB power specifications. No external sense resistor is needed, and no blocking diode is 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. The charge voltage is fixed at 4.2V, and the charge current can be programmed externally with a single resistor. The ME4054 automatically terminates he 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 ME4054 automatically enters a low current state, dropping the battery drain current to less than 2μA.The ME4054 can be put into shutdown mode, reducing the supply current to 25μA.