Dimmable LED light fixture having adjustable color temperature

摘要

Electronic circuitry for color-mixing in an LED light fixture during AC power dimming is disclosed to achieve adjustable color temperature. According to one embodiment, a dimmable LED light fixture has first, second, and third LED light sources, the first and second LED light sources producing white light, the third LED light source producing colored light, the LED driver configured to power the LED light sources by providing a single-channel variable-DC current source having two output terminals, and a current regulator for maintaining the current in the third LED light source path substantially constant as the LED driver output current is decreased when the AC power is reduced by the dimmer module, thereby altering the color of the light produced by the combination of the LED light sources.

主权项

1. A dimmable LED light fixture comprising: first and second LED light sources, the first LED light source producing light visibly different in color from that of light produced by the second LED light source; an LED driver having two input terminals configured to be connected to a dimmable AC power source having a dimmer module, the LED driver configured to power the LED light sources by providing a single-channel variable-DC power output requiring no more than two electrical connections to the LED light sources, such that current from the LED driver flows into the first and second LED light sources via one of the two electrical connections, the first and second LED light sources coupled in parallel across the LED driver output; and a current regulator coupled in series with only the second LED light source and with the other of the two electrical connections, the current regulator being configured to maintain current in the second LED light source substantially constant as the LED driver DC output power is decreased, while current in the first LED light source decreases as the LED driver DC output power is decreased, the LED driver DC output power being decreased when the AC power is reduced by the dimmer module, thereby altering the color of light produced by combination of the first and second LED light sources.