Lighting control circuit for vehicle lighting fixture

摘要

Relative comparison is made between a voltage applied to the whole of the first through eighth LEDs and a voltage applied to the first LED by a comparator. When the voltage applied to the whole of the LEDs has relatively dropped with respect to the voltage applied to part of the LEDs, the comparator outputs a Low Level signal, assumes an abnormality that accompanies a short-circuit fault in any one of the LEDs and causes a ninth LED to illuminate. Meanwhile, relative comparison is made between a voltage applied to the whole of the first through eighth LEDs and a voltage applied to the first LED by another comparator. When the voltage applied to the whole of the LEDs has relatively dropped with respect to the voltage applied to part of the LEDs, the comparator outputs a Low Level signal, assumes an abnormality that accompanies a short-circuit fault in the first LED and causes a ninth LED to illuminate.