For battery powered display backlighting, there is a limit to how bright the display can be. To lessen the drain on the battery, the backlighting can be adjusted for ambient lighting conditions up to 700 lux. The lux is the SI unit of luminous emittance and is equal to one lumen per square meter. Devices like TVs and monitors that are not battery powered can adjust backlighting into the low thousands of lux. It is critical that ambient light sensors have linear response to light in these ranges like the Vishay sensors.