Li-Ion battery charger with smooth-switch-over four-stage control

This article presents an implementation of smooth-cutover four-stage control in a Li-ion battery charger circuit. When charging a fully-discharged battery, the circuit can change control methods automatically in the sequence of pre-charging, constant-current, combination and constant-voltage. The smooth cutover is achieved by combining the control signals from current loop and voltage loop near transition point. The charger IC is implemented in a 1.5 ¿m BCD (bipolar-CMOS-DMOS) technology. Simulation and measured results show that all main targets were well achieved.