Ambient Light Sensors Control LCD Backlighting

A family of analog and digital ambient light sensor (ALS) ICs permits efficient control of LED backlighting for LCD-equipped devices. The BH16xx analog devices provide a linear current output proportional to luminous intensity ranging from 0 to 100,000 lux. These units feature the company's unique three-level gain selection providing exceptional design flexibility in matching power consumption to the specific application requirements. The BH17xx series of digital devices integrate a 16-bit analog-to-digital converter that produces 1-lux resolution over a range of 0 to 65,000 lux. The devices' I2C output is designed for direct connection to a microcontroller or baseband processor. Two measurement resolution levels are provided, allowing design trade-offs between sampling time and performance. For example, with high-resolution sampling, optical noise such as fluorescent lamp flicker can be filtered out. Low resolution provides a shorter sampling time for applications such as GPS systems, where the light-level changes are dynamic. Both the analog and digital ALS ICs come in either a 1.6- by 1.6- by 0.55-mm WSOF5 surface-mount package or the 3.0- by 1.6- by 0.7-mm WSOF6 surface-mount package. ROHM SEMICONDUCTOR GMBH, Willich-Munchheide, Germany. +49 (0) 21 54-92 1-0.