SENSORS

LIGHT & OPTICALWhat is a light sensor?A light or photo sensor simply detects the amount orintensity of light on its surface and produces a proportionalanalog or digital signal from it. Light sensors can take theform of a simple photodiode, phototransistor, or CdS cell.More sophisticated light sensor integrated photodiodes withsignal amplification and conversion circuitry to provide analog(i.e. frequency and voltage) or digital (via I 2 C or SMBUS)output signals.A color sensor is designed to accurately derive the colorchromaticity and illuminance (intensity) of ambient light. Itintegrates photodiodes with red, blue, green filters and signalconversion and control circuitry to provide analog or digitaloutput signals.Important selection parametersPhoto Current is the current produced in a semiconductordevice resulting from its illumination.Dark Current is the minimum electric current though aphotodiode when in total darkness.Output Channel(s) defines the nature and count of outputsignals: ex: Red, Green, Blue, etc.Typical applicationsLight sensors are most often used in lighting control toconserve energy or for a more natural visual effect. Forexample, ambient light sensors are used to automaticallyswitch street lights and parking lot lighting ON and OFF.It is also used to control the brightness of display backlighting based on ambient light conditions to make it morecomfortable for human eye.LIGHT & OPTICALApplicationCasesAutomotiveIndustrialConsumerReal Life ExamplesCompartment lighting controlAlarmsSLR CamerasOutdoor lightingSolar panels controlStreet lights control37www.FutureElectronics.com/Sensors