Patent ID: 7868595

Claim:
A circuit for regulation, comprising: a switching regulator controller that is arranged to control a main switch and a synchronous switch to control regulation of an output voltage, wherein the switching regulator includes: an error circuit that is arranged to provide an error signal that is based, in part, on a difference between a feedback signal and a reference voltage, wherein the feedback signal is based, at least in part, on an output voltage; a main switch control circuit that is arranged to provide a switch control signal based, in part, on the error signal; a zero-cross detection circuit that is arranged to provide a zero-cross detect signal, and to assert the zero-cross signal if an inductor current associated with the regulation of the output voltage is less than or equal to a pre-determined current level, wherein the pre-determined current level is zero or relatively near zero; and a synchronous switch control circuit that is arranged to provide a synchronous switch control signal such that the synchronous switch control signal is based, in part, on the switch control signal, and such that: during soft-start, the synchronous switch control circuit controls a synchronous switch such that the switching regulator controller controls non-synchronously-rectified regulation of the output voltage; and during non-synchronously-rectified regulation, if a soft-start done signal is asserted, and the zero-cross signal is not asserted for a pre-determined period of time, controlling the synchronous switch such that the regulation is changed from non-synchronously-rectified regulation to synchronously-rectified regulation.