A switching-based Li-ion battery charger without any additional compensation circuit is proposed. The proposed charger adopts a dual-current sensor and a current window control to ensure system stability in different charge modes: trickle current, constant current, and constant voltage. The proposed Li-ion battery charger has less chip area and a simpler structure to design than a conventional Li-ion battery charger with pulse width modulation. Simulation with a 1000µF capacitor as the battery equivalent, a 5V input, and a 1A charge current resulted in a charging time of 1.47ms and a 91% power efficiency.