An integrated circuit (IC) includes circuitry configured to, drive a flash unit comprising at least one light-emitting device, by providing a supply voltage to the flash unit based on an external input power source or a battery, the supply voltage being provided along one of a plurality of different current paths corresponding to a plurality of operation states, no voltage being received from the external input power source in a first operation state among the plurality of operation states, a first voltage level being received from the external input power source in a second operation state among the plurality of operation states, and a second voltage level being received from the external input power source in a third operation state among the plurality of operation states, and charge the battery based on an charging voltage received from the external input power source.