After chip-level-flashing a Ivy Bridge Dell laptop (Inspiron 15R SE 7520) with a corrupted BIOS chip (the BIOS spontaneously corrupted in 2014 then I fried the EC trying to reflash the BIOS, but that's a story for another time), I was disappointed to find that the backlight was dimmed using PWM at 200 Hz (a period of 5ms).
