TAOS TSL2560 EVM User Manual

TSL2560/61 EVM
User's Guide
An Evaluation System for the TSL2560/61 LTD Ambient Light Sensor
ALS I
NTRODUCTION
TAOS' Light-to-Digital (LTD) Ambient Light Sensor (ALS) solution can be used to automatically adjust
the brightness level of a computer display under a wide range of lighting conditions. As one of the
primary benefits of using TAOS' ALS, battery life can be significantly extended by minimizing the
necessary power required to luminate a display under various lighting conditions. In PC notebooks,
for example, the display panel and inverter (which delivers the power to the display panel) comprise
approximately one-third (1/3) of the total power consumption. TAOS' ALS helps control the display
backlight and keypad illumination in portable equipment like notebooks, PDAs, and cell phones. There
are other applications supported by the ALS which include street light control, security lighting,
sunlight harvesting, machine vision and automotive instrumentation clusters.
TAOS' ALS can also help extend the longevity of the LCD lamp life by automatically controlling the
display brightness or luminance. Lamp life depends strongly on the lamp current and is directly
proportional to display brightness levels. Unnecessarily over-driving the display with high operating
currents and excessive brightness will prematurely degrade the lamp life of a display. Automatically
controlling the illuminance to extend lamp life is beneficial in a variety of applications:
Mobile users who frequently use notebook computers in different ambient lighting conditions
Digital monitors with on-screen controls to extend the display life and lower power consumption
Kiosks that continuously operate 24/7 in sunlight or artificial lighting
Automatically adjusting automobile display clusters (e.g. for navigation system) for safety to retain
the driver's eyes on the road ahead at all times and eliminate glare to achieve better visibility at
night
Thirdly, since TAOS' ALS closely approximates the response of the human eye, it can also help
improve visual performance. While eyestrain is not believed to permanently damage one's eyes or
cause a loss of vision, it can be very uncomfortable and lead to a loss of productivity. Using TAOS'
ALS, excessive display brightness can be eliminated and productivity can be increased by maintaining
an optimal brightness level under various lighting conditions.
E M
VALUATION ODULE
The TSL2560/61 EVM helps facilitate evaluation of the TAOS' LTD ALS. A Universal Serial Bus (USB)
evaluation module is available which simply connects to the USB port of a personal computer.
Figure 1 is a picture of the USB evaluation module.
The TSL2560/61 device combines a visible light blocking photodiode with a broadband photodiode on
a single CMOS integrated circuit. This combination enables either device to be used to calculate light
intensity in lux over an effective 20-bit dynamic range with a 16-bit resolution without the use of an
expensive filter. Two integrating analog-to-digital converters (ADC) convert the photodiode currents
O
VERVIEW
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