Patent ID: 8497629

Claim:
A color-temperature-tunable device, comprising: one or more first light emitting diode (LED) chips comprising at least one first LED chip configured to emit a first light having a first peak wavelength, the one or more first LED chips driven by a first driving current provided by a first power source; one or more second LED chips comprising at least one second LED chip configured to emit a second light having a second peak wavelength, the second peak wavelength being different from the first peak wavelength, the one or more second LED chips driven by a second driving current provided by a second power source; and a wavelength converting layer above at least a portion of the one or more first LED chips and at least a portion of the one or more second LED chips, wherein a total driving current comprising the first driving current and the second driving current is kept approximately constant while the first driving current and the second driving current are different from one another.