Conduction mode (CRM) control in digital power supply using mosfet drain-to-source edge detection

A power converter, comprising:

• a DC-DC converter including a high-side transistor and a low-side transistor, the DC-DC converter being operable to convert an input voltage to an output voltage;
• pulse width modulation (PWM) circuitry configured to generate a high-side control signal for the high-side transistor and generate a low-side control signal for the low-side transistor to thereby cause conversion of the input voltage to the output voltage;
• a comparator configured to assert its output in response to a drain-to-source voltage of the low-side transistor being greater than a set threshold voltage;
• time-shift capture circuitry configured to measure a time shift between a falling edge of the low-side control signal and a time at which the comparator is asserted;
• time-shift control circuitry configured to determine a time shift error as a difference between a dead time and the measured time shift, with the dead time being a time between the falling edge of the low-side control signal and a rising edge of the high-side control signal;
• frequency adjustment circuitry configured to generate an output signal indicative of a frequency of the high-side control signal and the low-side control signal, based upon the time shift error, that would maintain the DC-DC converter as operating in critical conduction mode;
• and
• a policy circuit configured to generate a PWM control signal for the PWM circuitry, based upon the output signal from the frequency adjustment circuitry;
• wherein the PWM circuitry operates based upon the PWM control signal.