Switch-mode multi-power-supply Li-ion battery charger with power-path management

A switch-mode Li-ion battery charger is proposed. It is suitable for input power supply of wall adaptor or USB port in modern portable apparatus. When it works under USB port supply, its input current is automatically limited at a presetting value. A power-path management is introduced in to realize charging and power supply simultaneously based on load priority. It also realizes smooth transition from constant current charging to constant voltage charging in switch mode controller. The proposed charger is designed and simulated in TSMC 0.35μm CMOS process and all the simulation results are consistent with expectations well.