An example of a power supply system includes a switching voltage regulator comprising at least one switch configured to conduct an input current to generate an output voltage responsive to a switching signal and based on an input voltage. The system also includes a current regulator configured to generate a current sample voltage based on an amplitude of the input current relative to a reference current defining a maximum average amplitude setpoint of the input current to set a switching time defining a switching period of the at least one switch. The system also includes a switch controller configured to provide the switching signal to control the at least one switch based on an amplitude of the output voltage relative to a reference voltage and based on the switching time.