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PDF LX1972 Data sheet ( Hoja de datos )
| Número de pieza | LX1972 | |
| Descripción | Ambient Light Detector | |
| Fabricantes | Microsemi Corporation | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de LX1972 (archivo pdf) en la parte inferior de esta página. Total 9 Páginas | ||
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LX1972
www.DataSheet4U.com
TM ® Ambient Light Detector
PRODUCTION SPECIFICATION
DESCRIPTION
The LX1972 is a low cost silicon Dynamic range is determined by the
light sensor with spectral response that resistors (typically in the range of 10K
closely emulates the human eye.
to 100K) and power supply values.
Patented circuitry produces peak Typically the LX1972 needs only 1.8V
spectral response at 520nm, with IR of headroom to operate at 1000 Lux
response less than ±5%, of the peak illumination.
response, above 900nm.
Internal temperature compensation
The photo sensor is a PIN diode array allows dark current to be kept below
with a linear, accurate, and very 200nA over the full specification
repeatable current transfer function. temperature range (-40 to +85°C),
High gain current mirrors on the chip providing high accuracy at low light
multiply the PIN diode photo-current levels. Usable ambient light conditions
to a sensitivity level that can be range is from 1 to more than 5000 Lux.
voltage scaled with a standard value The LX1972 is optimized for
external resistor. Output current from controlling back lighting systems in low
this simple to use two-pin device can cost consumer products such as LCD
be used directly or converted to a TV, portable computers, and digital
voltage by placing it in series with a cameras.
single resistor at either of its two pins.
IMPORTANT: For the most current data, consult MICROSEMI’s website: http://www.microsemi.com
Protected By U.S.Patents: 6,787,757; Patents Pending
PRODUCT HIGHLIGHT
VDD
VDD
1.2V Typical
@ 100 Lux
LX1972
VSS
VSS
KEY FEATURES
Near Human Eye Spectral
Response
Very Low IR Sensitivity
Highly Accurate & Repeatable
Output Current vs. Light
Scalable Output Voltage
Temperature Stable
Integrated High Gain Photo
Current Amplifiers
No Optical Filters Needed
APPLICATIONS
Portable Electronic Displays
LCD TV Backlight Systems
Digital Still Cameras (DSC)
Desk top Monitors
Notebook Computers
Ambient Light
PACKAGE ORDER INFO
TA (°C)
Plastic 1206
BC 2-Pin
RoHS Compliant / Pb-free
-40 to 85
LX1972IBC
Note: Available in Tape & Reel. Append the letters “TR” to
the part number. (i.e. LX1972IBC-TR)
LX1972 Top View
Copyright © 2004
Rev. 1.1b, 2005-10-31
Microsemi
Integrated Products Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 1
1 page  
LX1972
www.DataSheet4U.com
TM ® Ambient Light Detector
PRODUCTION SPECIFICATION
SIMPLIFIED BLOCK DIAGRAM
VDD
Current
Amp
Figure 3 – Simplified Block Diagram
VSS
APPLICATION NOTE
LIGHT UNITS
In converting from µW/cm2 to lux it is necessary to
define the light source. Lux is a unit for the measurement
of illuminance, which is the photometric flux density or
visible light flux density. Whereas µW/cm2 is a
measurement of irradiance or the measurement of
electromagnetic radiation, flux both visible and invisible.
The first step in the conversion process is to convert
irradiance to illuminance, which essentially involves
running the irradiant flux through a photopic filter. In
normal ambient, a photopic curve is used and in dark
ambient, a scotopic curve (dark adapted eye) is used. If
the light is composed of only one wavelength, a
conversion chart will tell the conversion factor to convert
µW/m2 to lux (lumens/m2). If more than one wavelength
is used, the light spectrum of the irradiance must be
applied to the photopic filter to determine the resultant
illuminance. The most sensitive wavelength for the
normal light adapted human eye is 555nm, which
corresponds to yellowish-green light. At 555nm, the
conversion factor is 683 Lux = 1W/m2 = 100µW/cm2.
Therefore 14.6µW/cm2 = 100 lux at 555nm.
If the photo sensor had a truly photopic response, it would
produce the same output current for the same number of lux,
regardless of the color of the light. However, because the
match is not perfect, there is still wavelength dependency
particularly at the ends of the visible spectrum.
In the case of the LX1972 the peak photo response is at
520nm, however depending on the light source, what the
human eye perceives as ‘white’ light may actually be
composed of peak wavelengths of light other than 520nm.
For instance, a typical fluorescent lamp includes dominant
light not only near 550nm but also at 404 and 435nm.
Incandescent light sources such as standard tungsten lights
generate substantial IR radiation out beyond 2000nm.
For ease of automatic testing of the LX1972 the ATE
(automatic test equipment) light source is configured with
white LED’s whose current is adjusted to output a calibrated
flux density at 550nm. This allows consistent and repeatable
testing of the sensor but corresponds to a light source unlike
that typically found in a office, home or sunlit environment.
In practice, the user needs to place the sensor in the target
environment and calibrate the sensors output current range to
match the application objective. This is easily accomplished
by adjusting the output resistor, which sets the sensor’s gain.
Copyright © 2004
Rev. 1.1b, 2005-10-31
Microsemi
Integrated Products Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 5
5 Page | ||
| Páginas | Total 9 Páginas | |
| PDF Descargar | [ Datasheet LX1972.PDF ] | |
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