US Patent No. 10,034,346

DIM TO WARM CONTROLLER FOR LEDS


Patent No. 10,034,346
Issue Date July 24, 2018
Title Dim To Warm Controller For Leds
Inventorship Yifeng Qiu, San Jose, CA (US)
Jeroen Den Breejen, San Jose, CA (US)
Assignee Lumileds LLC, San Jose, CA (US)

Claim of US Patent No. 10,034,346

1. A control circuit for a light emitting diode (LED) lighting system for achieving a dim-to-warm effect between a minimum brightness-maximum dimming level, and a maximum brightness-minimum dimming level, the control circuit comprising:a clamp circuit coupled to a set of warm correlated-color-temperature (“CCT”) LEDs;
a switch coupled to a set of cool CCT LEDs;
an LED controller configured to:
sense the magnitude of an adjustable input current;
control the clamp circuit to clamp current through the set of warm CCT LEDs to a clamp current level based on the input current; and
control the switch to switch on the set of cool CCT LEDs responsive to the input current being greater than a first threshold level and to switch off the set of cool CCT LEDs responsive to the input current being lower than the first threshold level; and
a feedback circuit coupled to the clamp circuit and switch, the feedback circuit being configured to cause the clamp circuit to divert current from the set of warm CCT LEDs to the set of cool CCT LEDs in response to the input current exceeding a second threshold level.