Auto-tuning power supply

An apparatus for and method of automatically tuning a voltage regulation control loop for a digitally controlled switch mode power supply is provided. The method includes determining a frequency response of the power stage and calculating an open loop transfer function from the frequency response. A correlated metric is defined based at least in part on the open loop transfer function, wherein the correlated metric is correlated to an expected disturbance in regulated output voltage from the digitally controlled switch mode power supply due to a change in load. New values for the open loop transfer function are calculated for a range of controller compensation parameters to minimize the correlated metric. These values are then applied to the digital controller for use in controlling the power supply.