Switching Battery Charger Integrated Circuit for Mobile Devices in a 130-nm BCDMOS Process

Abstract

A switching battery charger integrated circuit (IC) for a mobile device is described which can regulate the system supply voltage and charge a Li-ion battery simultaneously. The charging current level is adaptively controlled according to the system load current and a battery can be forced to supply current to the system load when the input power is not sufficient. In order to allow a mobile device to supply power to peripheral devices, the battery charger IC can also be configured to operate as a boost dc-dc converter with the reversed direction of power flow. The operation mode of the battery charger IC is smoothly switched by adopting a diode-based mode selection scheme. Implemented in a 130-nm BCDMOS process, the battery charger IC occupies 12.25 mm(2) and has been verified to provide the appropriate charging profile for a Li-ion battery and regulate the system supply voltage under various operating conditions. The maximum charging current is 1.5 A and the output voltage ranges from 2.5 to 4.2 V. The maximum power efficiency of dc-dc conversion is 90% and 92%, respectively, for the buck and boost modes.