Patent ID: 8884599

Claim:
A DC-DC converter control circuit for controlling a high-side power transistor and a low-side power transistor connected in series between supply terminals to which an input supply voltage is applied, a converter switching node at the interconnection of the power transistors being adapted for connection of an inductor to which a load is connected, the control circuit comprising a feedback loop that provides a pulse width modulated control signal, logic circuitry to which the pulse width modulated control signal is applied and gate drivers with inputs connected to outputs of the logic circuitry and outputs applying gate drive signals to the gates of the power transistors; the control circuit further comprising: a circuit for periodically providing a gate drive signal to turn off the low-side power transistor earlier than an end of a cycle; digital detection circuitry operable when the gate drive signal for the low-side transistor is periodically turned off prior to the end of the cycle for providing a digital signal indicative of whether the converter switching node is at a potential above or below a zero reference at a time of a turn-off edge of the gate drive signals for the low-side power transistor; and adjusting circuitry controlled by the digital signal to advance or delay the turn-off edge of said gate drive signal for the low-side power transistor by a predetermined amount in response to the value of the digital signal, wherein the adjusting circuitry comprises a finite state machine which in response to the value of said digital signal advances or delays the turn-off edge of said gate drive signal.