TECH NOTES: Avago Technologies - RGB LED color mixing using linear dimming techniques

July 4, 2007
Avago Technologies describes the use of color management controllers in RGB LED color mixing.
This paper describes RGB LED color mixing control using linear dimming with Avago Technologies' color management controllers, ADJD-J823 and HDJD-J822.

The evaluation circuit consists of the LED backlight driver board, the HDJD-JD04 kit, and a small LED backlight screen. The LED driver board has a field sequencing mode to sequence the RGB colors.

DLP application The color mixing performance (i.e. du'v' measurements) is taken during linear dimming with and without field sequencing. The control measurement is taken with PWM dimming and the du'v' is computed.

From the results, linear dimming with or without field sequencing is a viable method to achieve precise RGB color control. The maximum du'v' result obtained is 0.006.

One possible application in linear dimming is the DLP projector.

This paper also explains why the pixel memory synchronization can be easily resolved with linear dimming.

Download the Avago paper (PDF, 400K)