A High-Efficiency Digitally Controlled RGB Driver for LED Pixels

Red-green-blue (RGB) light-emitting diodes (LEDs) are finding widespread use due to recent advances in the LED technology. In this paper, a microcontroller-based RGB driver was designed to drive a 3 3 RGB display panel. The proposed driver maintains the minimum drive voltage across the LEDs and current controllers required to keep it in regulation by selecting the minimum drain voltage of the MOSFETs of the current controllers; leading to reduced power dissipation in the MOSFET and increased efficiency in the LED string. The proposed LED driver system is also able to dim each individual LED in the pixel through a dimming controller circuit. Efficiencies of 85%, 90%, and 90% for the red, green, and blue LEDs, respectively, were experimentally verified at the maximum rated current for the RGB driver.