Patent ID: 8630103

Claim:
A controller for use in a power converter, comprising: a control circuit coupled to receive a feedback signal representative of an output of the power converter, the control circuit coupled to control a switching of a power switch of the power converter in response to the feedback signal to control a transfer of energy from an input of the power converter to the output of the power converter; an internal programming interface circuit coupled to the control circuit; a coupling switcher coupled to the internal programming interface circuit; an external programming terminal selectively coupled to the internal programming interface circuit through the coupling switcher, wherein an external programming circuit coupled to the external programming terminal is coupled to the internal programming interface circuit through the coupling switcher during a startup programming condition and during a fault condition of the power converter, wherein the external programming circuit coupled to the external programming terminal is decoupled from the internal programming interface circuit by the coupling switcher during a normal operating condition of the power converter.