Power factor correction circuit arrangement

Claim 2

A power factor correction converter, comprising: a switch for modulating an input current received from a rectified alternating-current supply so as to form an output voltage across an energy storage element in response to a switch control signal; a series-coupled resistor pair coupled across inputs of the alternating-current supply and having an intermediate node; a first feedback loop for forming the switch control signal in response to a signal formed at the intermediate node; and a second feedback loop for adjusting a resistance of the series-coupled resistor pair in response to a level of the output voltage.

Claim 3

The power factor correction converter according to claim 1 , further comprising a current sensing resistor coupled between a ground node and one of the inputs of the alternating-current supply.

Claim 4

The power factor correction converter according to claim 2 , wherein the intermediate node is held to a virtual ground level.

Claim 5

The power factor correction converter according to claim 1 , wherein the first feedback loop comprises an integrator coupled to receive the signal formed at the intermediate node.

Claim 6

The power factor correction converter according to claim 1 , wherein a comparator compares an integrated signal formed by the integrator to a periodic ramp signal.

Claim 7

The power factor correction converter according to claim 5 wherein the periodic ramp signal has a fixed amplitude.

Claim 8

The power factor correction converter according to claim 5 wherein the periodic ramp signal has a varying amplitude that is representative of a level of the alternating current supply.

Claim 9

The power factor correction converter according to claim 1 , wherein the adjusted resistance of the series coupled resistor pair comprises a fixed resistor coupled in series with a transistor.

Claim 10

The power factor correction converter according to claim 8 , including an integrated circuit controller and further comprising means for providing operating power for the integrated circuit controller under start-up conditions, wherein the means for providing is coupled to the transistor.

Claim 11

The power factor correction converter according to claim 9 , wherein the means for providing comprises a diode, wherein the diode passes current from the rectified alternating current supply under start-up conditions and wherein the diode is reverse biased after start-up.

Claim 12

The power factor correction converter according to claim 10 , where the means for providing comprises a switch wherein the switch passes current from the rectified current supply for providing power to the integrated circuit under start-up conditions and wherein the switch passes current from the rectified current supply to the intermediate node after start-up.

Claim 15

The method according to claim 12 , where said equalizing comprises modulating a power switch coupled to receive the input current.

Claim 16

The method according to claim 13 , wherein said equalizing further comprises integrating a signal representative of a difference between the first and second sensing signals.

Claim 17

The method according to claim 14 , wherein said equalizing further comprises forming the signal representative of the difference between the first and second sensing signals at a virtual ground node.

Claim 18

The method according to claim 14 , wherein said equalizing further comprises comparing the integrated signal to a periodic ramp signal and wherein a duty cycle of the switch is controlled by results of said comparing.

Claim 19

The method according to claim 12 , wherein said adjusting comprises modulating a resistance value.

Claim 20

The method according to claim 17 , wherein a current passing through the resistance value contributes to one of the first or second sensing signals.

Claim 21

The method according to claim 17 , wherein said modulating comprises: forming an error signal representative of the output voltage; and controlling a transistor based upon a level of the error signal.

Claim 24

The method according to claim 20 , further comprising disabling the switch control signal upon an output voltage reaching a first predetermined level and enabling the switch control signal upon the output voltage falling to a second predetermined level, wherein the second predetermined level is lower than the first predetermined level.

Claim 25

The method according to claim 21 , further comprising integrating the difference signal thereby forming an integrated signal.

Claim 26

The method according to claim 22 , further comprising: comparing the integrated signal to a periodic ramp signal; and forming the switch control signal in response to said comparing.

Claim 27

The method according to claim 23 wherein the periodic ramp signal has a fixed amplitude.

Claim 28

The method according to claim 24 wherein the periodic ramp signal has a varying amplitude that is representative of a level of the alternating current supply.

Claim 29

A controller for power factor correction converter, comprising: switch modulation circuitry for modulating an input current received from an alternating-current supply so as to form an output voltage across an energy storage element; output voltage regulating circuitry coupled to the switch modulation circuitry for disabling switching upon the output voltage reaching a first predetermined level and for enabling switching upon the output voltage falling to a second predetermined level, wherein the second predetermined level is lower than the first predetermined level; and input voltage and current sensing circuitry coupled to the switch modulation circuitry for maintaining the input current in phase with the input voltage in a feedback loop, wherein the input voltage and current sensing circuitry receives a control signal formed at a virtual ground node, the control signal being representative of a difference between the input current and the input voltage.

Claim 30

A controller for power factor correction converter, comprising: switch modulation circuitry for modulating an input current received from an alternating-current supply so as to form an output voltage across an energy storage element; output voltage regulating circuitry coupled to the switch modulation circuitry for disabling switching upon the output voltage reaching a first predetermined level and for enabling switching upon the output voltage falling to a second predetermined level, wherein the second predetermined level is lower than the first predetermined level; and input voltage and current sensing circuitry coupled to the switch modulation circuitry for maintaining the input current in phase with the input voltage in a feedback loop, wherein the input voltage and current sensing circuitry receives a control signal formed at a virtual ground node, the control signal being representative of a difference between the input current and the input voltage.

Claim 31

The controller according to claim 26 , further comprising an integrator coupled to receive the control signal formed at the virtual ground node.

Claim 32

The controller according to claim 27 , further comprising a comparator for comparing an integrated signal formed by the integrator to a periodic ramp signal and for generating the switch control signal in response to results of the comparison.

Claim 33

The controller according to claim 28 , wherein the controller is implemented as an integrated circuit having no more than eight pins.

Claim 34

The controller according to claim 29 , wherein the controller includes means for disabling switching in the event of an over-current condition.

Claim 35

A controller for power factor correction converter, comprising: switch modulation circuitry for modulating an input current received from an alternating-current supply so as to form an output voltage across an energy storage element; input voltage and current sensing circuitry coupled to the switch modulation circuitry for maintaining the input current in phase with the input voltage in a feedback loop, wherein the input voltage and current sensing circuitry forms a first sensing signal representative of an input current received from a alternating-current supply, a second sensing signal representative of an input voltage received from the supply and a difference signal representative of a difference between the first sensing signal and the second sensing signal; and output voltage regulating circuitry coupled to the switch modulation circuitry for forming an error signal representative of the output voltage and for adjusting a level of one of the first and second sensing signals in response to the error signal.

Claim 36

A controller for power factor correction converter, comprising: switch modulation circuitry for modulating an input current received from an alternating-current supply so as to form an output voltage across an energy storage element; input voltage and current sensing circuitry coupled to the switch modulation circuitry for maintaining the input current in phase with the input voltage in a feedback loop, wherein the input voltage and current sensing circuitry forms a first sensing signal representative of an input current received from a alternating-current supply, a second sensing signal representative of an input voltage received from the supply and a difference signal representative of a difference between the first sensing signal and the second sensing signal; and output voltage regulating circuitry coupled to the switch modulation circuitry for forming an error signal representative of the output voltage and for adjusting a level of one of the first and second sensing signals in response to the error signal.

Claim 37

The controller according to claim 31 , further comprising an integrator coupled to receive the difference signal.

Claim 38

The controller according to claim 32 , further comprising a comparator for comparing an integrated signal formed by the integrator for a periodic ramp signal and for generating the switch control signal in response to results of the comparison.

Claim 39

The controller according to claim 33 , wherein the controller is implemented as an integrated circuit having no more than eight pins.

Claim 40

The controller according to claim 34 , wherein the output voltage regulating circuitry comprises means for disabling switching upon the output voltage reaching a first predetermined level and for enabling switching upon the output voltage falling to a second predetermined level, wherein the second predetermined level is lower than the first predetermined level.

Claim 41

The controller according to claim 34 , wherein the controller includes means for disabling switching in the event of an over-current condition.