Patent ID: 8089216

Claim:
A flyback controller for generating a switching signal for controlling the delivery of input current into a primary winding of a transformer in a flyback converter that has a secondary winding in the transformer and that is driven by AC output from a dimmer control that is chopped at a phase angle based on a setting of the dimmer control, the flyback controller being configured to: generate the switching signal with a duty cycle that causes the average output current in the secondary winding of the transformer to be at a substantially constant but controllable level, the flyback controller including: a tracking input configured to receive a dimmer output tracking signal that is representative of the instantaneous magnitude of the output from the dimmer control; an averaging circuit configured to average the dimmer output tracking signal so as to generate an average dimmer output signal that is representative of a time-averaged value of the dimmer output tracking signal; cause the average output current in the secondary winding of the transformer to vary as a function of the average dimmer output signal when the phase angle exceeds a threshold; and wherein the flyback controller is configured to receive a desired average output current signal representative of a desired average output current in the secondary winding of the transformer and wherein the controller is configured to adjust the switching signal to cause the average output current in the secondary winding of the transformer to substantially track the desired average output current signal when the average dimmer output signal is greater than the desired average output current signal, and to substantially track the average dimmer output signal when the average dimmer output signal is less than the desired average output target current signal.