METHOD AND SYSTEM FOR DIMMING AC-POWERED LIGHT EMITTING DIODE (LED) LIGHTING SYSTEMS USING CONVENTIONAL INCANDESCENT DIMMERS
First Claim
1. A dimming control circuit for dimming at least one light emitting diode responsive to an AC power signal from a dimming circuit, the control circuit comprising:
- a power stage adapted to receive the AC power signal and coupled to each light emitting diode, the power stage operable responsive to first control signals to provide current to each light emitting diode;
a current control loop circuit coupled to the power stage and operable to control the power stage to provide current to each of the light emitting diodes, the current having a value determined by a control value signal;
an AC detector coupled to the power stage and operable to detect an instantaneous value of the AC power signal and to generate an AC presence signal indicating whether the AC power signal is present or absent; and
a current control circuit operable responsive to the AC presence signal to generate the control value signal that is applied to the current control loop to control the current through each light emitting diode via the control value signal and achieve the desired dimming, and the current control circuit further operable to limit inrush current from the AC power signal.
3 Assignments
0 Petitions
Accused Products
Abstract
A dimming control circuit for dimming light emitting diodes receives an AC input voltage signal from a dimming circuit. The control circuit includes a power stage and a current control loop coupled to the power stage. An AC detector is operable to detect an instantaneous value of the AC input voltage signal and to generate a signal indicating whether the AC input voltage signal is present or absent. A current control circuit is operable responsive to the signal to adjust the operation of the current control loop and to control current through the light emitting diodes to achieve the desired dimming, and to prevent inrush current on the AC input voltage signal.
-
Citations
20 Claims
-
1. A dimming control circuit for dimming at least one light emitting diode responsive to an AC power signal from a dimming circuit, the control circuit comprising:
-
a power stage adapted to receive the AC power signal and coupled to each light emitting diode, the power stage operable responsive to first control signals to provide current to each light emitting diode; a current control loop circuit coupled to the power stage and operable to control the power stage to provide current to each of the light emitting diodes, the current having a value determined by a control value signal; an AC detector coupled to the power stage and operable to detect an instantaneous value of the AC power signal and to generate an AC presence signal indicating whether the AC power signal is present or absent; and a current control circuit operable responsive to the AC presence signal to generate the control value signal that is applied to the current control loop to control the current through each light emitting diode via the control value signal and achieve the desired dimming, and the current control circuit further operable to limit inrush current from the AC power signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
-
-
13. A method of dimming at least one strand of series-connected light emitting diodes being power by a power stage, the method comprises:
-
controlling the conduction angle of an AC power signal, the AC power signal having a half cycle; calculating a full-scale count value associated with a half cycle of the AC power signal; calculating a conduction angle count value corresponding to the actual portion of each half cycle of the AC power signal that is supplied to each strand of series-connected light emitting diode; from the conduction angle and full scale count values, generating a control signal; and from the control signal, deriving a set point value that adjusts the operation of the power stage to dim the strands series-connected light emitting diodes - View Dependent Claims (14, 15, 16)
-
-
17. An electronic system, comprising:
-
electronic circuitry coupled to at least one light emitting diode strand, the electronic circuitry including a dimming control circuit for dimming at least one light emitting diode responsive to an AC power signal from a dimming circuit, the control circuit comprising; a power stage adapted to receive the AC power signal and coupled to each light emitting diode, the power stage operable responsive to first control signals to provide current to each light emitting diode; a current control loop circuit coupled to the power stage and operable to control the power stage to provide current to each of the light emitting diodes, the current having a value determined by a control value signal; an AC detector coupled to the power stage and operable to detect an instantaneous value of the AC power signal and to generate an AC presence signal indicating whether the AC power signal is present or absent; and a current control circuit operable responsive to the AC presence signal to generate the control value signal that is applied to the current control loop to control the current through each light emitting diode via the control value signal and achieve the desired dimming, and the current control circuit further operable to limit inrush current from the AC power signal. - View Dependent Claims (18, 19, 20)
-
Specification