Reduction of audible noise in a power converter

A power converter, comprising:

• an energy transfer element coupled between an input of the power converter and an output of the power converter;
• a power switch coupled to the energy transfer element and the input of the power converter;
• a sense circuit coupled to generate a feedback signal representative of the output of the power converter;
• and
• a controller coupled to the power switch, wherein the controller includes:
• a drive circuit coupled to generate a drive signal to control switching of the power switch in response to a current sense signal representative of a current through the power switch, and in response to a feedback signal, to control a transfer of energy from the input of the power converter to the output of the power converter;
• an audible noise window circuit coupled to generate a frequency skip signal in response to the feedback signal, wherein the audible noise window circuit is coupled to activate the frequency skip signal in response to a frequency of a feedback request signal responsive to the feedback signal being within an audible noise window;
• and
• an audible noise reduction circuit coupled to output a reduction signal in response to the frequency skip signal, wherein the drive circuit is coupled to generate the drive signal in response to the reduction signal from the audible noise reduction circuit.

A power converter, comprising:

• an energy transfer element coupled between an input of the power converter and an output of the power converter;
• a sense circuit coupled to generate a feedback signal representative of the output of the power converter;
• a power switch coupled to the energy transfer element and the input of the power converter;
• a primary controller coupled to generate a drive signal to control switching of the power switch in response to the feedback signal to control a transfer of energy from the input of the power converter to the output of the power converter;
• a synchronous rectifier circuit comprising a switch coupled the output of the power converter;
• a secondary controller coupled to generate a secondary control signal coupled to be received by the synchronous rectifier circuit to rectify the output of the power converter in response to the feedback signal;
• and
• an audible noise reduction circuit coupled to generate a reduction signal in response to the secondary control signal received from the secondary controller, wherein the reduction signal is coupled to alter the feedback signal to prevent a switching frequency of the power switch from falling into an audible noise range.