A High-Efficiency Integrated Multimode Battery Charger With an Adaptive Supply Voltage Control Scheme

A high-efficiency multimode battery charger with an adaptive supply voltage (ASV) control scheme is presented in this paper. The proposed battery charger includes a charging circuit and a dc-dc buck converter. The charging circuit automatically switches among trickle current (TC), constant-current (CC), and constant-voltage (CV) modes corresponding to the battery voltage while the buck converter with ASV control generates an ASV to closely track the battery voltage, leading to significant reduction in the power loss of the charging circuit. To further enhance the efficiency of the battery charger, zero-current detection and nonswitching control schemes are employed to decrease the power consumption of the buck converter in TC and CV modes. The battery charger was implemented with a 0.35- μm CMOS 2P4M process. The experimental results are shown to verify the theoretical analysis of the proposed charger. The maximum efficiency of the overall system is 88.3%, and the maximum efficiency improvement between the proposed charger and the conventional linear charger with fixed supply voltage is up to 11.6%.