An apparatus comprises a switching circuit, an error amplifier circuit, a current threshold circuit, and an over-current detection circuit. The switching circuit provides a switching duty cycle that includes a charge portion and a discharge portion. The error amplifier circuit generates an error signal representative of a difference between a target voltage value and a voltage at an output of the voltage regulator circuit. The switching circuit adjusts the switching duty cycle to regulate the voltage at the output using the error signal and a reference waveform signal. The current threshold circuit generates an adaptive peak current limit threshold. The over-current detection circuit generates an over-current signal when the reference waveform signal satisfies the adaptive peak current limit threshold during the charging portion of the switching cycle. The switching circuit interrupts one or more switching cycles when the reference waveform signal satisfies the adaptive peak current limit threshold.