A tunable white light bulb is a dimmable, spectrally adjustable LED lamp that can operate with a variable color temperature and lumen output. White light is a mix of many different wavelengths in the visible part of the electromagnetic spectrum. Not all white light is created equal. Different combinations of wavelengths give white light different color characteristics. A wavelength mixture laden with a higher percentage of radiant energy emitted at the long-wavelength (red) part of the spectrum has a “warm white” appearance. White light with a blue-enriched spectrum exhibits a “cool” appearance. The perceived warmth or coolness of white light is commonly communicated using a color metric known as color temperature. The concept of color temperature is based on the comparison of the apparent color of the light being produced by a source to that of an ideal blackbody radiator. The chromaticity coordinates of artificial light sources other than tungsten filament lamps typically do not lie exactly on the blackbody or Planckian locus. These light sources may be characterized as having a correlated color temperature (CCT).