Control circuit for synchronous rectifiers in DC/DC converters to reduce body diode conduction losses

An apparatus for providing first and second control signals in a switching power supply having a pulse width modulator (PWM) providing a PWM signal, a first switch having first, second, and third terminals and a parasitic body diode, the second terminal being a control terminal and coupled to the first control signal, and a second switch having first, second, and third terminals and a parasitic body diode, the second terminal being a control terminal and coupled to the second control signal, the apparatus comprising:

• a feedback controller including:
• a variable delay module receiving as an input the PWM signal and operative to provide a plurality of outputs, each output being a time delayed PWM pulse, each of which is delayed by a unique delay time;
• a turn-off module receiving as input signals the PWM signal and a measurement signal indicative of the conduction of the parasitic body diode, the turn-off module monitoring the first control signal and the measurement signal and operative in response to the measurement signal and the first control signal to select one of the plurality of outputs of the delay module to adjust the turn-off time of the second control signal relative to the PWM signal to substantially minimize the time that the parasitic body diode of the second switch is conducting.