Abstract: A design for a Li-ion battery charger IC that can operate in a constant current-constant voltage (CC-CV) charge mode is proposed.In the CC-CV charge mode,the charger IC provides a constant charging current at the beginning,and then the charging current begins to decrease before the battery voltage reaches its final value.After the battery voltage reaches its final value and remains constant,the charging current is further reduced.This approach prevents charging the battery with full current near its saturated voltage,which can cause heating.The novel design of the core of the charger IC realizes the proposed CC-CV charge mode.The chip was implemented in a CSMC 0.6μm CMOS mixed signal process.The experimental results verify the realization of the proposed CC-CV charge mode.The voltage of the battery after charging is 4.1833V.

Key words: Li-ion battery charger, constant current-constant voltage charge modes, CMOS analog circuit