Patent ID: 8599582

Claim:
A control circuit for use in a power converter, the control circuit comprising: a feedback circuit coupled to receive a feedback signal representative of an energy requirement at an output of the power converter and to generate an enable signal in response thereto; a drive signal generator coupled to the feedback circuit to generate a drive signal to control switching of a power switch in response to the enable signal to regulate the output of the power converter to a regulation output voltage value; an unregulated dormant mode and output reset control circuit coupled to power down the drive signal generator for a first period of time such that the regulation of the output of the power converter is ceased in response to the enable signal indicating that the energy requirement at the output of the power converter has fallen below a first threshold, wherein the drive signal generator is unresponsive to the enable signal when powered down during the first period of time, and wherein the unregulated dormant mode and output reset control circuit powers up the drive signal generator in response the first period of time elapsing such that the drive signal generator is again responsive to the enable signal; and a counter coupled to be enabled for a second period of time in response to the unregulated dormant mode and output reset control circuit powering up the drive signal generator, wherein the counter counts cycles of a clock signal for which the enable signal indicates an increase in the energy requirement at the output of the power converter, wherein the counter is coupled to disable the drive signal generator for a third period of time in response to a count of the counter reaching a threshold number, such that a voltage at the output of the power converter is discharged to a value that is less than the regulation output voltage value.