Lighting system with power factor correction control data determined from a phase modulated signal

1. A light emitting diode (LED) lighting system comprising:

a controller comprising:

an input to receive a phase delay signal indicating a phase delay of a phase modulated dimmer signal; and

a signal processor, coupled to the input, to receive the phase delay signal and determine a control operating parameter from the phase delay signal and to generate a switch control signal using the determined operating parameter to vary an input current to a switching power converter with a phase modulated voltage and to maintain a regulated link voltage at an approximately constant value until a duty cycle of the control signal decreases to a predetermined threshold value and to decrease the regulated link voltage of the switching power converter when the duty cycle of the control signal decreases to the predetermined duty cycle threshold value.

2. The LED lighting system of claim 1 further comprising:

the switching power converter coupled to the controller; and

a load coupled to the switching power converter, wherein the load includes one or more light emitting diodes.

3. The LED lighting system of claim 2 further comprising a time-based phase delay detector to detect the phase delay of the phase modulated signal and generate the phase delay signal as a digital signal.

4. The LED lighting system of claim 2 wherein the operating parameter is a peak voltage of the phase modulated dimmer signal.

5. The LED lighting system of claim 2 wherein the phase delay signal indicates a dimming level and the controller is further configured to generate a switch control signal to cause the switching power converter to respond to the dimming level indicated by the signal without decreasing an effective resistance of the switching power converter, as perceived by a voltage source of the switching power converter, as the dimming level indicated by the signal increases.

6. The LED lighting system of claim 2 wherein the controller is further configured to generate approximately constant pulse widths for the switch control signal during each cycle of phase modulated signal when a duty cycle of switch control signal is below the predetermined duty cycle threshold value.

7. The LED lighting system of claim 2 wherein the controller is further configured to generate pulses for the switch control signal during the phase delays of the phase modulated signal, wherein the pulse widths and duty cycles of the pulses of the switch control signal generated during the phase delays are sufficient to attenuate ripple of the phase modulated signal during the phase delays of phase modulated signal.

8. The LED lighting system of claim 7 wherein the pulses of switch control signal generated during the phase delays have a period significantly greater than a period of the pulses of the switch control signal during an active period of phase modulated signal.

9. A method of controlling a light emitting diode (LED) lighting system, the method comprising:

receiving a phase delay signal indicating a phase delay of a phase modulated dimmer signal;

determining a control operating parameter from the phase delay signal using a signal processor; and

generating a duty cycle modulated switch control signal using the determined operating parameter to vary an input current to a switching power converter with a phase modulated voltage and to maintain a regulated link voltage at an approximately constant value until a duty cycle of the switch control signal decreases to a predetermined threshold value and to decrease the regulated link voltage of the switching power converter when the duty cycle of the switch control signal decreases to the predetermined duty cycle threshold value.

10. The method of claim 9 further comprising:

receiving the switch control signal at a terminal of a switch in the switching power converter;

converting the phase modulated dimmer signal into the regulated link voltage; and providing power to a load coupled to the switching power converter, wherein the load includes one or more light emitting diodes.

11. The method of claim 10 further comprising:

detecting the phase delay of the phase modulated signal using a time-based phase delay detector; and

generating the phase delay signal as a digital signal.

12. The method of claim 10 wherein the operating parameter is a peak voltage of the phase modulated dimmer signal.

13. The method of claim 10 wherein the phase delay signal indicates a dimming level, the method further comprising:

generating the switch control signal to cause the switching power converter to respond to the dimming level indicated by the signal without decreasing an effective resistance of the switching power converter, as perceived by a voltage source of the switching power converter, as the dimming level indicated by the signal increases.

14. The method of claim 10 further comprising:

generating approximately constant pulse widths for the switch control signal during each cycle of phase modulated signal when a duty cycle of switch control signal is below a predetermined threshold.

15. The method of claim 10 further comprising:

generating pulses for the switch control signal during the phase delays of the phase modulated signal, wherein the pulse widths and duty cycles of the pulses of the switch control signal generated during the phase delays are sufficient to attenuate ripple of the phase modulated signal during the phase delays of phase modulated signal.

16. The method of claim 15 wherein the pulses of switch control signal generated during the phase delays have a period significantly greater than a period of the pulses of the switch control signal during an active period of phase modulated signal.

17. A light emitting diode (LED) lighting system comprising:

a controller comprising:

an input to receive a phase delay signal indicating a phase delay of a phase modulated dimmer signal; and

a signal processor, coupled to the input, to receive the phase delay signal and determine a control operating parameter from the phase delay signal and to generate a switch control signal using the determined operating parameter to control an input current in response to one or more values of the phase delay signal; and

wherein the controller is further configured to decrease a duty cycle of the switch control signal as the dimming level decreases until the dimming level reaches a dimming level threshold and to keep the duty cycle of the switch control signal approximately constant for dimming levels below the dimming level threshold.

18. The lighting system of claim 17 further comprising a time-based phase delay detector to detect the phase delay of the phase modulated signal and generate the phase delay signal as a digital signal.

19. A light emitting diode (LED) lighting system comprising:

a controller comprising:

an input to receive a phase delay signal indicating a phase delay of a phase modulated dimmer signal; and

a signal processor, coupled to the input, to receive the phase delay signal and determine a control operating parameter from the phase delay signal and to generate a switch control signal using the determined operating parameter to control an input current in response to one or more values of the phase delay signal;

wherein the controller is further configured to increase an effective resistance of the switching power converter as the dimming level indicated by the dimming signal decreases.