Abstract: An integrated regulator and charging system including a DC/DC converter, a P-channel device, a battery system and a system/charger controller. The DC/DC converter converts an input voltage to a regulated voltage on a system bus. The battery system includes a rechargeable battery and a current sense device coupled in series between the drain of the P-channel device and ground, where the source of the P-channel device is coupled to the system bus. The system charger/controller regulates the system bus at a minimum voltage level when the battery voltage is below the minimum voltage level, such as a deeply discharged battery. The system charger/controller also regulates charge current through the battery when its voltage is between the minimum voltage level and a maximum voltage level and regulates the system bus at the maximum voltage level when the battery voltage is at the maximum voltage level.