Sensor Converts Light’s Intensity To Digital Signals

With the TSL2550 sensor, the intensity of ambient light can be converted to digital signals that, in turn, can be used to control the backlighting of display screens found in portable equipment, such as laptops, cell phones, PDAs, camcorders, and GPS systems. By allowing display brightness to be adjusted to ambient conditions, the sensor is expected to bring about a significant reduction in the power dissipation of portables. The device can also be used to monitor and control commercial and residential lighting conditions. The TSL2550 all-silicon sensor combines two photodetectors, with one of the detectors sensitive to both visible and infrared light and the other sensitive only to IR light. The photodetectors’s output is converted to a digital format, in which form the information can be used to approximate the response of the human eye to ambient light conditions sans the IR element, which the eye cannot perceive. The information can also be used to calculate the ratio of IR to visible light to determine the source of the ambient light (e.g., incandescent, fluorescent, sunlight, etc.). Besides the photodetectors, the TSL2550 sensor also packs a companding A/D converter and SMBus interface. The device operates from a 2.7V-5.5V supply and comes in an 8-pin SOIC package costing $1.59 each/1,000. For more details, call Carlo Strippoli at TEXAS ADVANCED OPTOELECTRONIC SOLUTIONS, Plano, TX. (972) 673-0759.