Fairchild Korea Semiconductor Ltd.

Samsung Electronics Co., Ltd.

Kyung-Hee Jang

Sang-Woo Lee

Nak-Choon Choi

Maeng-Ho Seo

A power factor correction circuit is disclosed which is comprised of a boost converter that generates an output voltage to a secondary load according to operation of the switch. The circuit also includes a switching controller which multiplies together a secondary side error voltage of the boost converter and a voltage representative of the input current of the boost converter. The switching controller compares the multiplied voltage with a reverse sawtooth wave voltage, and controls the switch of the boost converter according to the comparison results.

Power factor correction (PFC) circuit

A power factor compensation controller for use in a switching power supply having a switch, an inductor, and upper and lower reference signals that are proportional to an input voltage to the switching power supply includes a multiplier that multiplies an error signal and a signal representative of a current in the switch to produce a multiplier output signal. The power factor compensation controller further includes an adder that adds the multiplier output signal to the lower reference signal to produce an adder output signal and a comparator that compares the adder output signal to the upper reference signal to produce a comparator output signal. The power factor compensation controller also includes a flip-flop that receives the comparator output signal and a clocking signal and a logic gate that receives an output of the flip-flop and the clocking signal to produce a gating signal for controlling the conduction of the switch so that an envelope of peak currents in the switch is substantially in-phase with the input voltage to the switching power supply.

Power factor compensation controller

Disclosed is a Power Factor Correction (PFC) controller which comprises a boost converter, an error amplification unit, a calculator, and a switching driver. The error amplification unit reduces the error voltage of the output voltage of the boost converter to a specific reference voltage. The calculator receives first and second input voltages proportional to the input power of the converter and the output voltage of the error amplification unit, and outputs the voltage proportional to the first input voltage and the output voltage of the error amplification unit and inversely proportional to the second input voltage. The switching driver controls the switch to OFF when the voltage which detects the current flowing to switch of the boost converter becomes equal to the output voltage of the calculator, and controls the switch to ON when the zero current of the coil of the boost converter is detected.

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Kyungki-do, South Korea

Kyung-Hee Jang