A circuit, system, and method for tracking energy use in a electronic circuit. A circuit includes a DC-DC converter and a comparator. The DC-DC converter is configured to maintain a desired output voltage by switching energy to an energy storage device based on an output voltage of the energy storage device. The DC-DC converter includes an output driver configured to source current to the energy storage device. The comparator is coupled to the DC-DC converter. The comparator is configured to identify a drive state of the output driver, and to generate a signal indicative of amount of energy transferred from the DC-DC converter to a load circuit. The signal corresponds to the identified drive state.