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 ( μ AFSs) with a micro-LED ( μ LED) array are highly demanded for their controllability of individual LEDs. However, the integration of a μ LED 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 μ LED is adaptively controlled with pulse width modulation (PWM) in conjunction with an additional PWM control for temperature calibration. Experimental results with a 16 × 16 μ LED array placed on top of the proposed driver show that a 5-bit PWM signal controls the average current through each μ LED 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 μ AFSs driver is as high as 92.3%.