High frequency partial boost power factor correction control circuit and method

A circuit for providing power factor correction comprising a boost converter circuit having a boost inductance and a power factor correction switch coupled in series with the boost inductance, the boost inductance and power factor correction switch being coupled across the output of a rectifier being supplied with AC power from an AC line, the boost converter circuit further comprising a boost diode coupled to a junction between the inductor and the switch, an output of the boost diode coupled to an output capacitor, a DC bus voltage being provided across the output capacitor, further comprising a control circuit receiving as inputs a rectified AC input voltage from the rectifier, a signal proportional to current through the inductor and the DC bus voltage across the capacitor, and wherein the control circuit provides a pulse width modulated signal to control the on time of the PFC switch, further comprising an enable/disable circuit receiving as inputs the rectified AC input voltage and the DC bus voltage, the circuit instantaneously comparing the rectified AC input voltage and the DC bus voltage and controlling the control circuit whereby the control circuit provides the pulse width modulated signal to control the PFC switch when the rectified AC input voltage is less than the DC bus voltage and disables the generation of the pulse width modulated signal to the PFC switch when the rectified AC input voltage is greater than DC bus voltage.