Method and apparatus for implementing an unregulated dormant mode with an event counter in a power converter

摘要

A control circuit for use in a power converter with an unregulated dormant mode of operation includes a drive signal generator coupled to generate a drive signal to control switching of a power switch in response to an energy requirement of one or more loads to be coupled to the power converter output. An unregulated dormant mode control circuit is included and is coupled to render dormant the drive signal generator when the energy requirement of the one or more loads falls below a threshold for more than a first period of time. The unregulated dormant mode control circuit is coupled to power up the drive signal generator after a second period of time has elapsed. The drive signal generator is coupled to again be responsive to changes in the energy requirement of the one or more loads after the second period of time has elapsed.