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10 February 2009 An ultra-low-power ambient light sensor for portable devices
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Power management is one of the most important issues in portable electronics like cell phone, PDA, UMPC, GPS, MP3 player and laptop computer. Ambient Light Sensors are getting popular as a most effective solution to extend battery lifetime for these devices. This paper provides basic information about ambient light sensors on a general level and introduces an ultra low-power ambient light sensor for portable electronics. The implemented ambient light sensor converts light illuminance to 5-digital codes every 300ms which can measure illuminance from 10 to 1000 Lux consuming only 5uA. An IR-reject optical filter and a built-in integrating analog-to-digital converter reduce influences of infrared ray and 50Hz/60Hz noise from artificial light sources respectively. The ambient light sensor is fabricated in a standard CMOS 0.5-um process technology. Test results show that the implemented ambient light sensor has incandescent/fluorescent light sensitivity ratio around 2.3.
© (2009) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Soon-Ik Cho, Yun-Jeong Kim, Jong-Ho Lee, Kwang-Hyun Baek, and Suki Kim "An ultra-low-power ambient light sensor for portable devices", Proc. SPIE 7219, Optoelectronic Integrated Circuits XI, 72190U (10 February 2009);

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