An apparatus comprises a voltage supply configured to provide an input voltage, a buck-boost converter coupled to the voltage supply and comprising an inductor, and a buck-boost controller coupled to the power supply and the buck-boost converter. The buck-boost controller comprises a mode controller coupled to the buck-boost converter and a comparator coupled to the mode controller and the buck-boost converter. The comparator is configured to compare an error signal based on an output voltage of the buck boost-converter to an output current of the inductor to produce a control signal. The mode controller is configured to control the output voltage at least in part according to the control signal.