Load control device for a light-emitting diode light source having different operating modes
First Claim
1. A circuit for controlling an intensity of a light-emitting diode (LED) light source, the circuit 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;
a current sense circuit configured to provide a load current feedback signal that indicates the magnitude of the load current; and
a control circuit configured to generate at least one drive signal for controlling the LED drive circuit to control an average magnitude of the load current to adjust the intensity of the LED light source towards a target intensity;
wherein the control circuit is configured to;
operate in a first state and a second state on a periodic basis over a plurality of burst periods, each of the plurality of burst periods including a first time period and a second time period;
control the LED drive circuit in the first state during the first time period in which the control circuit adjusts a value of an operational characteristic of the at least one drive signal to regulate a peak magnitude of the load current towards a target current in response to the load current feedback signal;
control the LED drive circuit in the second state during the second time period in which the control circuit maintains the operational characteristic of the at least one drive signal approximately constant;
when the target intensity is within a first intensity range, adjust the average magnitude of the load current by keeping a length of the first time period constant and adjusting a length of the second time period; and
when the target intensity is within a second intensity range, adjust the average magnitude of the load current by keeping the length of the second time period constant and adjusting the length of the first time period.
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Accused Products
Abstract
A load control device for regulating an average magnitude of a load current conducted through an electrical load may operate in different modes. The load control device may comprise a control circuit configured to activate an inverter circuit during an active state period and deactivate the inverter circuit during an inactive state period. In one mode, the control circuit may adjust the average magnitude of the load current by adjusting the inactive state period while keeping the active state period constant. In another mode, the control circuit may adjust the average magnitude of the load current by adjusting the active state period while keeping the inactive state period constant. In yet another mode, the control circuit may keep a duty cycle of the inverter circuit constant and regulate the average magnitude of the load current by adjusting a target load current conducted through the electrical load.
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Citations
20 Claims
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1. A circuit for controlling an intensity of a light-emitting diode (LED) light source, the circuit 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; a current sense circuit configured to provide a load current feedback signal that indicates the magnitude of the load current; and a control circuit configured to generate at least one drive signal for controlling the LED drive circuit to control an average magnitude of the load current to adjust the intensity of the LED light source towards a target intensity; wherein the control circuit is configured to; operate in a first state and a second state on a periodic basis over a plurality of burst periods, each of the plurality of burst periods including a first time period and a second time period; control the LED drive circuit in the first state during the first time period in which the control circuit adjusts a value of an operational characteristic of the at least one drive signal to regulate a peak magnitude of the load current towards a target current in response to the load current feedback signal; control the LED drive circuit in the second state during the second time period in which the control circuit maintains the operational characteristic of the at least one drive signal approximately constant; when the target intensity is within a first intensity range, adjust the average magnitude of the load current by keeping a length of the first time period constant and adjusting a length of the second time period; and when the target intensity is within a second intensity range, adjust the average magnitude of the load current by keeping the length of the second time period constant and adjusting the length of the first time period. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method of controlling an intensity of a light-emitting diode (LED) light source, the method comprising:
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generating at least one drive signal for controlling an LED drive circuit to adjust an average magnitude of a load current conducted through the LED light source to adjust the intensity of the LED light source towards a target intensity; receiving a load current feedback signal that indicates the magnitude of the load current; operating in a first state and a second state on a periodic basis over a plurality of burst periods, each of the plurality of burst periods including a first time period and a second time period; controlling the LED drive circuit in the first state during the first time period in which a value of an operational characteristic of the at least one drive signal is adjusted to regulate a peak magnitude of the load current towards a target current in response to the load current feedback signal; controlling the LED drive circuit in the second state during the second time period in which the operational characteristic of the at least one drive signal is maintained approximately constant; when the target intensity is within a first intensity range, adjusting the average magnitude of the load current by keeping a length of the first time period constant while adjusting a length of the second time period; and when the target intensity is within a second intensity range, adjusting the average magnitude of the load current by keeping the length of the second time period constant while adjusting the length of the first time period. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification