Temperature-Aware Adaptive Control for Automotive Front-Lighting System

Adaptive front-lighting systems (AFSs) have been widely adopted to automotive industries for providing higher driver's safety. As their light sources, multi-string light-emitting diodes (LED) arrays have been widely adopted because of their simpler driver controls. Recently, micro-structured AFSs (μAFSs) with a micro-LED (μLED) array are highly demanded for their controllability of individual LEDs. However, the integration of a μLED array and its high-power active-matrix driver are not available on the market. Moreover, a high-power driver causes not only a significant variation in driving current, but also a higher power density requiring over-temperature protection (OTP). In this paper, the average current through each μLED is adaptively controlled with pulse width modulation (PWM) in conjunction with an additional PWM control for temperature calibration. Experimental results with a 16 × 16 μLED array placed on top of the proposed driver show that a 5-bit PWM signal controls the average current through each μLED cell up to 11 mA. The maximum current error of 4.11% at 100 °C is reduced to 0.23%. When OTP is enabled, the amount of average pixel current reduction depends on the given temperature. The maximum power efficiency of the proposed μAFSs driver is as high as 92.3%.