Mode operation detection for control of a power converter with an active clamp switch

A controller for use in a power converter, the controller comprising:

• a control circuit coupled to receive an input line voltage sense signal representative of an input voltage of the power converter, the control circuit coupled to generate a control signal in response to the input line voltage sense signal, wherein the control signal represents a delay time between turning OFF a clamp switch and turning ON a power switch of the power converter, the control circuit comprising:
• a first comparator coupled to compare the input line voltage sense signal and a first threshold;
• and
• a second comparator coupled to compare the input line voltage sense signal and a second threshold,
• wherein the control circuit is coupled to generate a first mode of operation signal in response to the first comparator and is coupled to generate a second mode of operation signal in response to the second comparator,
• wherein the delay time is a delay time in response to the first mode of operation signal or the delay time is a delay time in response to the second mode of operation signal, the delay time in response to the second mode of operation signal is greater than the delay time in response to the first mode of operation signal;
• and
• a drive circuit coupled to generate a drive signal to control the turn ON and turn OFF of the power switch to transfer energy from an input of the power converter to an output of the power converter in response to the control signal.