Color tempearature depends on what parameter


Newly Enlightened
Jul 8, 2014
Hello master's
i am start to study behavior of lights. So i have a doubts that if i used perticular LED having of 1w. So color temperature of the light depends on which parameter.
means if i used PWM that is 40% then what will happen??


Apr 15, 2010
Brisbane, Australia
Colour temperature is primarily dictated by the phosphor composition and to a degree the thickness etc of the posphor; ie. the physical construction of the LED. Yes to certain degree the amount of current applied can shift the tint, but not radically, you can't change a 6500K LED to output 4000K by changing it's supplied power.

Subjective testing suggests that de-doming some LEDs can result in a warmer tint, but it is far from an exact science.
If you want a certain temperature and tint, then you really have to order it, there's no magic fix for something that's not right.


Flashlight Enthusiast
Aug 21, 2009
South Hill, VA
You are asking the wrong question in a few threads. Start with What is CCT? When you see why the CCT of a filament is lower than that of sunlight, and can guess what the CCT of a red-hot machine part must be, you are able to ask the right question: Spectral Distribution depends on what parameters? How does this affect CRI, CCT, and Tint?

Most white LEDs are built on a blue diode. This emits blue light in a narrow distribution.

A phosphor is deposited atop this. It absorbs blue photons and emits photons in a range of colors - Red, orange, yellow, green. Deep purple will not be present, so extremely purple flowers may look strange. Deep purple pigments are rare otherwise.

This phosphor is covered in a protective material to protect it from oxidation. If this material were flat, some light would be re-reflected into the phosphor, increasing heat retention, decreasing output, and changing the color distribution. Restriking photons can down-convert again to a redder color. To reduce restrike and internal reflection, this protective covering is domed.

So changing the Dome, the Phosphor, the Die will change the Spectral power distribution. This is the whole symphony we describe with the terms CRI, CCT, and Tint.
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