An information handling system inverter powers a display backlight at variable brightness levels determined by a brightness module integrated in the inverter. The brightness module sums a user interface setting, automated brightness setting and ambient light sensor measurement input into the inverter to determine the inverter power output, thus simplifying the integration of user brightness settings with automated brightness adjustments, such as DPST adjustments. A brightness range register holds maximum and minimum brightness settings for output by the brightness module. A calibration register holds a calibration brightness setting for calibration of display brightness.