US Patent No. 10,257,904


Patent No. 10,257,904
Issue Date April 09, 2019
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. 10,257,904

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:
control the clamp circuit to clamp current through the set of warm CCT LEDs to a clamp current level based on an input current; 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.