Patent ID: 8405362

Claim:
A circuit for providing system power and charging a battery, comprising: a switching regulator configured for transmitting the system power based on an input power and a duty cycle; a duty cycle generator configured for generating the duty cycle to be used to regulate power output from the circuit in response to an input-current limit control circuit, a battery-current limit control circuit, and a battery-voltage limit control circuit; the input-current limit control circuit configured for limiting the duty cycle based on a limit of an input current; the battery-current limit control circuit configured for limiting the duty cycle based on a limit of a battery charging current; the battery-voltage limit control circuit configured for limiting the duty cycle based on a limit of a battery voltage; a controllable impedance element for nominally coupling the battery to the system; and an output voltage regulation circuit configured for controlling the controllable impedance element, the controllable impedance element partially or substantially decoupling the battery from the system in response to the voltage of the system dropping to or below a system voltage limit.