Patent attributes
An integrated circuit power factor controller includes a pulse width modulator and a line sensing circuit. The pulse width modulator has a first input for receiving a feedback signal, a second input for receiving a line sense signal, and an output for providing a drive signal having a duty cycle formed in response to the feedback signal and the line sense signal. The line sensing circuit has an input for receiving the drive signal, and an output coupled to the second input of the pulse width modulator for providing the line sense signal. The line sensing circuit forms the line sense signal in response to measuring a duty ratio of the drive signal. In another form, an offline converter includes an integrated circuit power factor controller that provides a line sense signal in response to a duty ratio of the drive signal without measuring a voltage on the input line.
