The A4055 is a complete constant-current / constant-voltage linear charger for single cell lithium-Ion batteries. 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 A4055 automatically terminates the charge cycle when the charge current drops to 1/10 the programmed value after the final float voltage is reached. https://www.campuscomponent.com/products/ait-semiconductor-battery-management-ic_a4055e5r-ic-589-d/2208614000001843654