Hardware implementation of digitaly controlled colour temperature tuneable white light

Light Emitting Diodes have fundamentally altered several of the dynamics within the industry itself and the technology has been touted as fourth generation lighting technology. With LED lighting controllers, the coloured LEDs have launched a new dimension in architectural lighting. RGB LED lighting fixtures offer endless colour changing possibilities to enhance environment in an interior. The forward characteristics of Red, Green and Blue LEDs indicate the region of control to produce acceptable level of light intensities because the intensity of light produced by an LED is proportional to its forward current. In this paper, a digital controller based RGB driver was designed to enable the operation of the LED cluster for various shades of white. The proposed LED driver system is also able to adjust duty cycle of each individual LED through a digital controller circuit. The proposed driver maintains the minimum drive voltage across the RGB LEDs and current controllers required to keep it in regulation by selecting the minimum drain voltage of the MOSFETs. The developed system is tested for its photometric characteristics. The Lumen output of the source developed remained same when operated at different colour temperatures of white shades.