A power converter controller circuit is disclosed. In one aspect, a power converter controller circuit includes a control circuit to generate a switching signal to be coupled to a power switch to control power delivered to an output of a power converter. A timing circuit is to be coupled to the power switch and coupled to receive a feedback signal and the switching signal. The timing circuit is to disable the power switch from receiving the switching signal in response to the feedback signal after detection of a fault condition. The feedback signal repeatedly transitions between first and second states in response to the output when the power supply operates normally. The feedback signal maintains its state when the power supply is in the fault condition. The feedback signal transitions between the first and second states independently from the switching signal.