A Single-Chip 60-V Bulk Charger for Series Li-Ion Batteries With Smooth Charge-Mode Transition

In this paper, a single-chip 60-V battery charger prototype is presented. The newly proposed charge mode transition can ensure smooth transitions between incremental current (IC), constant current (CC), and constant voltage (CV) modes. The charger sources a current of 136 mA in CC mode and has an efficiency up to 92% during the charging sequence. Intentional saturation of both the IC and CV regulation loops ensure the stability of the charger throughout the charging sequence. Bonding PAD designed to remove the constraints on the aspect ratio of input transistors as a prevention of antenna effect is also disclosed. The proposed design has been implemented on silicon using the TSMC 0.25 μm 1-poly 3-metal bipolar-CMOS-DMOS (BCD) 60-V process.