In the automotive information display device industry, products with high reliability and wide temperature conditions are required, and interest in products that do not cause lighting defects even under extremely low temperature conditions is increasing. In this experiment, we produced an LED backlight unit for car navigation in a cryogenic environment. And to make this backlight unit, we used 12 side-emitting white LEDs with 3[W] high power LEDs. This backlight unit emits up to 18,000[nits] at a power consumption of 36[W] and has a startup voltage time of less than 1[ms] at -50° ambient temperature.