TSL2581CS Ver la hoja de datos (PDF) - austriamicrosystems AG
Número de pieza
componentes Descripción
Fabricante
TSL2581CS Datasheet PDF : 33 Pages
| |||
TSL2581, TSL2583
LIGHT-TO-DIGITAL CONVERTER
TAOS134A − JULY 2012
APPLICATION INFORMATION: SOFTWARE
Calculating Lux
The TSL258x is intended for use in ambient light detection applications such as display backlight control, where
adjustments are made to display brightness or contrast based on the brightness of the ambient light, as
perceived by the human eye. Conventional silicon detectors respond strongly to infrared light, which the human
eye does not see. This can lead to significant error when the infrared content of the ambient light is high, such
as with incandescent lighting, due to the difference between the silicon detector response and the brightness
perceived by the human eye.
lid This problem is overcome in the TSL258x through the use of two photodiodes. 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 digital outputs. Channel 1
a digital output is used to compensate for the effect of the infrared component of light on the channel 0 digital
output. The ADC digital outputs from the two channels are used in a formula to obtain a value that approximates
v the human eye response in the commonly used Illuminance unit of Lux:
ill Chipscale Package
For CH1/CH0 = 0.00 to 0.25
For CH1/CH0 = 0.25 to 0.38
t For CH1/CH0 = 0.38 to 0.45
For CH1/CH0 = 0.45 to 0.60
G s For CH1/CH0 > 0.60
Lux = 0.105 CH0 − 0.208 CH1
Lux = 0.1088 CH0 − 0.2231 CH1
Lux = 0.0729 CH0 − 0.1286 CH1
Lux = 0.060 CH0 − 0.10 CH1
Lux/CH0 = 0
A t FN Package
s n For CH1/CH0 = 0.00 to 0.30
For CH1/CH0 = 0.30 to 0.38
e For CH1/CH0 = 0.38 to 0.45
m t For CH1/CH0 = 0.45 to 0.54
For CH1/CH0 > 0.54
Lux = 0.130 CH0 − 0.240 CH1
Lux = 0.1649 CH0 − 0.3562 CH1
Lux = 0.0974 CH0 − 0.1786 CH1
Lux = 0.062 CH0 − 0.100 CH1
Lux/CH0 = 0
a n The formulas shown above were obtained by optical testing with fluorescent and incandescent light sources,
o and apply only to open-air applications. Optical apertures (e.g. light pipes) will affect the incident light on the
device.
l c Simplified Lux Calculation
a Below is the argument and return value including source code (shown on following page) for calculating lux with
the TSL2583FN. The source code is intended for embedded and/or microcontroller applications. All floating
ic point arithmetic operations have been eliminated since embedded controllers and microcontrollers generally
do not support these types of operations. Because floating point has been removed, scaling must be performed
prior to calculating illuminance if the integration time is not 400 msec and/or if the gain is not 1× as denoted in
Techn the source code on the following pages.
Copyright E 2012, TAOS Inc.
20
r
www.taosinc.com
The LUMENOLOGY r Company
r
Share Link: 