Patent ID: 8324874

Claim:
An apparatus, comprising: a synchronous converter for providing a regulated output voltage responsive to an input voltage, a control PWM signal to a control switch of the synchronous converter and a synchronous PWM signal to a synchronous switch of the synchronous converter; and a first circuit for generating the control PWM signal and the synchronous PWM signal responsive to a PWM control signal, wherein the first circuit limits a maximum duty cycle of the synchronous PWM signal to a predetermined level, wherein the first circuit further comprises: a transistor for enabling provision of the synchronous PWM signal at a first logical level when the transistor is in an ON state and for enabling provision of the synchronous PWM signal at a second logical level when the transistor is in an OFF state; an AC coupling circuit for controlling the ON state and the OFF state of the transistor responsive to the PWM signal; and a second circuit for generating the synchronous PWM signal at a first logical level that turns off the synchronous switch of the synchronous converter during startup of the synchronous converter to maintain the synchronous converter in a diode mode of operation.