Load Control Device for a Light-Emitting Diode Light Source
First Claim
1. A light-emitting diode (LED) driver for controlling an intensity of an LED light source, the LED driver comprising:
- an LED drive circuit configured to control a magnitude of a load current conducted through the LED light source to control the intensity of the LED light source, the LED drive circuit including a controllable-impedance circuit adapted to conduct the load current through the LED light source; and
a control circuit operatively coupled to the controllable-impedance circuit of the LED drive circuit to control the intensity of the LED light source to a target intensity, the control circuit configured to control the controllable-impedance circuit to adjust a peak magnitude of the load current, the control circuit configured to control a duty cycle of the load current to adjust an average magnitude of the load current;
wherein the control circuit is configured to control the intensity of the LED light source by maintaining a frequency of the load current constant and adjusting an on time of the load current when the target intensity is above a predetermined threshold, and maintaining the on time of the load current constant and adjusting the frequency of the load current when the target intensity is below the predetermined threshold.
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Accused Products
Abstract
A load control device for controlling the intensity of a lighting load, such as a light-emitting diode (LED) light source, may include a power converter circuit operable to receive a rectified AC voltage and to generate a DC bus voltage, a load regulation circuit operable to receive the bus voltage and to control the magnitude of a load current conducted through the lighting load, and a control circuit operatively coupled to the load regulation circuit for pulse width modulating or pulse frequency modulating the load current to control the intensity of the lighting load to a target intensity. The control circuit may control the intensity of the lighting load by pulse width modulating the load current when the target intensity is above a predetermined threshold and control the intensity of the lighting load by pulse frequency modulating the load current when the target intensity is below the predetermined threshold.
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Citations
20 Claims
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1. A light-emitting diode (LED) driver for controlling an intensity of an LED light source, the LED driver comprising:
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an LED drive circuit configured to control a magnitude of a load current conducted through the LED light source to control the intensity of the LED light source, the LED drive circuit including a controllable-impedance circuit adapted to conduct the load current through the LED light source; and a control circuit operatively coupled to the controllable-impedance circuit of the LED drive circuit to control the intensity of the LED light source to a target intensity, the control circuit configured to control the controllable-impedance circuit to adjust a peak magnitude of the load current, the control circuit configured to control a duty cycle of the load current to adjust an average magnitude of the load current; wherein the control circuit is configured to control the intensity of the LED light source by maintaining a frequency of the load current constant and adjusting an on time of the load current when the target intensity is above a predetermined threshold, and maintaining the on time of the load current constant and adjusting the frequency of the load current when the target intensity is below the predetermined threshold. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification