A Monolithic High-Voltage Li-Ion Battery Charger With Sharp Mode Transition and Partial Current Control Technique

A high-voltage (HV) lithium-ion battery charger control chip with sharp mode transition and partial current control technique is proposed in this paper. The proposed sharp mode transition eliminates the transition region between constant current (CC) and constant voltage (CV) stages in traditional CC-CV chargers. This technique reduces the charging time and simplifies the compensator design. Furthermore, by adopting the HV partial current control technique, the charging current at the CC stage can be regulated only by sensing part of inductor current. The charger is designed and fabricated using Taiwan Semiconductor Manufacturing Company 0.25-mu m 1P3M bipolar CMOS-DMOS HV process. With a 25-V input voltage, the output voltage (i.e., battery voltage) may range from 6 to 22 V and the maximum charging current is 2.5 A. The peak efficiency reaches 97%, occurring at 1-A charging current.