US Patent No. 10,462,867

LOAD CONTROL DEVICE FOR A LIGHT-EMITTING DIODE LIGHT SOURCE HAVING DIFFERENT OPERATING MODES


Patent No. 10,462,867
Issue Date October 29, 2019
Title Load Control Device For A Light-emitting Diode Light Source Having Different Operating Modes
Inventorship Steven J. Kober, Center Valley, PA (US)
Assignee Lutron Technology Company LLC, Coopersburg, PA (US)

Claim of US Patent No. 10,462,867

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.