Method and apparatus to control a power converter having a low loop bandwidth

A controller for use in a power converter connected to an ac input, comprising:

• a feedback sensor circuit coupled to receive a feedback signal representative of an output of the power converter;
• a feedback sampling signal generator coupled to generate a feedback sampling signal coupled to be received by the feedback sensor circuit, wherein the feedback sensor circuit is coupled to sample the feedback signal in response to the feedback sampling signal;
• a state machine coupled to the feedback sensor circuit to control switching of a switch of the power converter circuit according to one of a plurality of operating condition states in response to the feedback sensor circuit, wherein each of the plurality of operating condition states includes a substantially fixed switch on time;
• and
• a feedback time period signal generator coupled to generate a feedback time period signal coupled to be received by the state machine, wherein a period of the feedback time period signal is substantially greater than a period of the feedback sampling signal, wherein the state machine is coupled to be updated in response to the feedback time period signal.