TSL2550-RS232EVM TAOS, TSL2550-RS232EVM Datasheet

Optical Sensor Development Tools Evaluation Module TSL2550

TSL2550-RS232EVM

Manufacturer Part Number
TSL2550-RS232EVM
Description
Optical Sensor Development Tools Evaluation Module TSL2550
Manufacturer
TAOS
Datasheet

Specifications of TSL2550-RS232EVM

Maximum Operating Temperature
+ 55 C
Minimum Operating Temperature
0 C
Description/function
Ambient Light Sensor
For Use With/related Products
TSL2550
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
TSL2550EVM
An Evaluation System for the TSL2550 Ambient Light Sensor
I
TAOS’ Ambient Light Sensor (ALS) solution can be used to automatically adjust the brightness level for
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 increased by minimizing the power required to illuminate a
display under various ambient lighting conditions. In PC notebooks, for example, the display panel
and inverter (which delivers the power to the display panel) account for approximately 33% 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 that include street light control, security lighting, digital cameras, sunlight harvesting,
automotive instrument clusters, and projection and big-screen televisions.
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:
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.
The TSL2550EVM helps facilitate evaluation of the TAOS Ambient Light Sensor (ALS). Two evaluation
module options are available which simply connect to a personal computer via a PCMCIA card slot or
serial communication port. Both evaluation modules include application software allowing the user to
easily control various features of the TSL2550 device. Figure 1 is a group picture of both evaluation
modules.
User’s Guide
NTRODUCTION
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
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TSL2550-RS232EVM Summary of contents

Page 1

... The TSL2550EVM helps facilitate evaluation of the TAOS Ambient Light Sensor (ALS). Two evaluation module options are available which simply connect to a personal computer via a PCMCIA card slot or serial communication port. Both evaluation modules include application software allowing the user to easily control various features of the TSL2550 device. Figure group picture of both evaluation modules ...

Page 2

... Environmental Parameters: Temperature: 0°C - 55°C Humidity 90% Software Installation: CD-ROM When the PC is turned off, the TSL2550 PCMCIA EVM card should be inserted into a PCMCIA card slot that allows light to reach the clear plastic aperture on top of the card. If possible, the ALS card should be placed on top ...

Page 3

... SXKey sticking out at 9 o’clock, use the four bottom header pins. Vss is the bottom pin. The external SMBus header pins (two identical 5-pin headers) are labeled on the housing’s panel cutout: +5 for Vdd, D for data, G for ground, and C for clock. See Figure 2 for a schematic diagram of the TSL2550 Serial EVM. ...

Page 4

... Figure 2. TSL2550 Serial EVM Schematic www.taosinc.com ...

Page 5

... See Figure 3 regarding a sample screen capture of the software. The EVM application constantly monitors the ambient light level through the use of two photodiodes on the TSL2550. One of the photodiodes (Channel 0) is sensitive to both visible and infrared light, while the second photodiode (Channel 1) is sensitive primarily to infrared light. An integrating ADC converts the photodiode currents to Channel 0 and Channel 1 digital outputs ...

Page 6

... The TSL2550 contains two ADC registers (channel 0 and channel 1). Each of the two ADC value registers contains seven bits. Bits 6 through 0 contain the 7-bit code representing the ADC count value that is proportional to the photodetector current. Each ADC register contains two components to determine the logarithmic ADC count value: “Chord” ...

Page 7

... Fluorescent Daylight (shade) Incandescent Table 3. TSL2550 Sensor Output Summary From Figure 3, the correlated color temperature of the ambient light source is roughly proportional to Ch0/Ch1 (i.e. the inverse of the ratio described in Table 3). This information may be useful in certain applications such as computer displays and television screens to perform color balance. ...

Page 8

... R ANGE The TSL2550 device has the ability to operate in “Standard” or “Extended” range mode. Normally the device operates in standard range. In standard range, the device can respond to ambient light conditions from, for example, approximately 0 to 1400 Lux under certain fluorescent lighting conditions. After about 1400 Lux, the device saturates and cannot produce valid results. ...

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