Energy tracking circuit

A method, comprising:

• driving, by a DC-DC converter, an energy storage device coupled to an output driver of the DC-DC converter;
• identifying, by a comparator coupled to the output driver, a drive state of the output driver;
• and
• generating, by the comparator, a signal indicative of amount of energy transferred to the energy storage device by the DC-DC converter, wherein the signal corresponds to the identified drive state.

An energy tracking system, comprising:

• a DC-DC converter 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 comprising an output driver configured to source current to the energy storage device;
• a comparator coupled to the DC-DC converter, the comparator configured to:
• identify a drive state of the output driver;
• and
• generate a signal indicative of amount of energy transferred to the energy storage device by the DC-DC converter, wherein the signal corresponds to the identified drive state;
• an energy accumulator coupled to an output of the comparator, the energy accumulator configured to measure energy flowing to the energy storage device over time based on the signal generated by the comparator.