Precise Individual Illumination Control of Matrix LED With Bypass Gate Driver and 8-Bit PWM

Precise illumination control of matrix light-emitting diode (LED) headlamps is crucial for both energy efficiency in electric vehicles and driver safety. Enhancing energy efficiency extends the range of electric vehicles, while ensuring reliable illumination improves driver safety in autonomous vehicles. This brief discusses the control of illumination for eight serially connected LEDs using 8-bit pulse-width modulation (PWM) combined with a gate driver. A bypass gate driver, employing a cascode current mirror structure, manages the current through each LED, minimizing variations in analog string voltage. The proposed method supports 256 levels of illumination adjustment, making it suitable for adaptive front-lighting systems (AFLS). Implemented with TSMC’s 180-nm high-voltage CMOS technology, with a maximum power supply of 70V and a chip size of 5 mm2, the system ensures precise LED control and effectively prevents overcurrent.