Slide 1OutlineReference listTo explore furtherMajor applicationsTypes of SensorsTypes of OutputsKey ParametersSelection Guidelines Log vs LinearSelection Guidelines Current, Voltage, Frequency or DigitalBasic Function Photo DiodeBasic Function Photo TransistorTypical Application CircuitsAmbient Light Sensor vs Light SensorHazardsHazards ContinuedPackagingManufacturesCostWhere to BuyECE5320 MechatronicsAssignment#01: Literature Survey on Sensors and Actuators Topic: Ambient Light SensorsPrepared by: Abe ClementsDept. of Electrical and Computer Engineering Utah State University3/7/200801/14/2019ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-2Outline –Reference list–To probe further–Major applications–Types of Sensors–Types of Outputs–Key Parameters–Selection Guidelines–Basic Function–Typical Application Circuits–Ambient Light Sensor vs Light Sensor–Hazards–Packaging–Cost–Where to Buy01/14/2019ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-3Reference list•http://www.avagotech.com/docs/AV02-0080EN•http://www2.electronicproducts.com/Choosing_an_ambient_light_sensor_to_optimize_OLED_performance-article-osram-sensors-feb2007-html.aspx•http://en.wikipedia.org/wiki/Photodiodes01/14/2019ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-4To explore further•https://event.on24.com/eventRegistration/EventLobbyServlet?target=registration.jsp&eventid=115623&sessionid=1&key=4075AADFA033DC4CCD3D248D67F227E3&partnerref=XXXX&sourcepage=register•http://www.avagotech.com/docs/AV00-0151EN01/14/2019ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-5Major applications •Backlight Dimming•Light Level Control•On/Off Control of Street LightsTypes of Sensors•Photo Diode•Photo Transistors•Many packages have internal signal conditioning to make interfacing with the sensors easier•Often Op-Amps will be included in the same package.01/14/2019ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-6Types of Outputs•Linear Output–Lux to Output follows linear gain•Logarithmic Output–Lux to Output follows a logarithmic curve•Light to Current Output–Outputs a current proportional to the detected light following a linear of log curve•Light to Voltage Output–Outputs a voltage proportional to the detected light following linear of log curve•Light to Frequency–Outputs a square wave or pulse train with the frequency of the signal proportional to the incident light•Digital–Light is converted to a digital signal often uses standard interfaces such as I2C01/14/2019ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-7Key ParametersParameter Description UnitsPeak Sensitivity Wavelength sensor is most sensitive to (close to 560 best for ambient light)nmDark Current Current device leaks when no light is present ASaturation Voltage/CurrentPoint at which device saturates V or APhoto Current Current output for specific luminance AOperating Temp Range of temperature under which sensor can function properlyCSupply voltage Voltage range over which part will operate V01/14/2019ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-8Selection Guidelines Log vs Linear•Logarithmic output is needed if large range is to be detected–For example ambient light detection for a back light on a mobile phone needs to detect near complete darkness to full sunlight–Converting to Lux is more complicated than linear•Linear best for smaller ranges–On/Off control of street lights if (its saturated then don’t turn light on)–Or devices intended for interior usage–Easier conversion to Lux01/14/2019ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-9Selection GuidelinesCurrent, Voltage, Frequency or Digital•Current –Output usually run though a resistor or Op amp to convert to Voltage–Requires extra parts–Allows selection of range/gain based on resistor value–Needs A/D to connect to microcontroller•Voltage– May not need extra parts to connect to microcontroller–Usually has an internal resistor(or op amp) to convert current to voltage–Needs A/D to connect to microcontroller•Frequency –Highly accurate –Does not require A/D to connect to microcontroller–Needs timing recovery to obtain information–Generally cheaper than digital, but more expensive than current or voltage•Digital –Easier interfacing to microcontroller –High accuracy –More expensive01/14/2019ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-10Basic Function Photo Diode•Usually the photo diode is placed is reversed biased•As light falls on the detector it induces a photo current through the diode01/14/2019ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-11Basic Function Photo Transistor•Are usually just bipolar transistors packaged in a transparent case•When light strikes the base collector junction a current is induced•The induced current is then amplified by the transistors gain01/14/2019ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-12Typical Application Circuits01/14/2019ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-13Ambient Light Sensor vs Light Sensor•The primary difference between light sensors and ambient light sensors is that spectral response of ambient light sensors is designed to closely match that of the human eye01/14/2019ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-14Response of Panasonic ams1Hazards•Human eye sensitive to 400nm to 700nm with peak sensitivity at 560nm•Many silicon light sensors are sensitive to IR and will detect show brighter light than humans perceive•Filters or proper sensor must be used to match the response of the human eye01/14/2019ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-15Hazards Continued•Current output from the photo sensors is very sensitive to temperature•All sensors at some point use a current to detect light so even frequency and voltage output sensors may be vulnerable•Some sensors have internal circuitry to compensate for temperature variations•If high accuracy is needed temperature variations will need to be accounted for01/14/2019ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-16Packaging01/14/2019ECE5320 Mechatronics. Assignment#1 Survey on sensors and
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