Ambient light sensors are also called illuminance or illumination sensors, optical sensors, brightness sensors or simply light sensors. One very important application for ALS technology is cell phones. In a cell phone, the ALS enables automatic control of display backlight brightness over a wide range of illumination conditions from a dark environment to direct sunlight. With the ALS input, a microcontroller (MCU) or baseband processor increases or decreases the display brightness depending on the environment. This control dramatically improves visibility and reduces power consumption since LCD backlighting can draw as much as 51% of the power in the input standby mode. In addition, the ALS signal can be used to instruct the keypad LED driver to minimize keypad backlighting reducing up to 30% of the power in the input standby power mode. In a bright environment, the LED keypad brightness is reduced for minimal power