Method of forming a power supply controller and structure therefor

摘要

In one embodiment, a method of forming a power supply controller includes forming the power supply controller to receive an input signal that is representative of an ac signal, and forming the power supply controller to form an average value of an output current over a period of a drive signal that is formed by the power supply controller to have a waveshape of substantially one of a squared version of the input signal or a waveshape of the input signal.

主权项

1. A power supply controller comprising:
an input configured to receive a first signal that is representative of an ac input voltage, the ac input voltage having a first period and having a first waveshape of a sine waveshape; a reference circuit including a first amplifier having an input that receives the first signal, the reference circuit configured to form a reference signal having a second waveshape of substantially the first waveshape squared; a PWM controller circuit configured to form a drive signal to control a switch to form an output current from a transformer, the drive signal having a second period, the PWM controller circuit configured to use the reference signal to control the switch to form a first average value of the output current over the first period to be substantially constant and form a second average value of the output current over the second period to have a third waveshape that is substantially the squared sine waveshape of the reference signal; and wherein the power supply controller is configured to receive from the transformer only signals from a primary winding of the transformer and not signals from a secondary winding.