LX1970MINI EVAL Microsemi Analog Mixed Signal Group, LX1970MINI EVAL Datasheet - Page 5

• Manufacturer Part Number: LX1970MINI EVAL
• Description: MINI LIGHT SENSOR BOARD
• Manufacturer: Microsemi Analog Mixed Signal Group

Specifications of LX1970MINI EVAL

• Sensor Type: Light, Current Output
• Interface: Analog
• Sensitivity: 520nm
• Voltage - Supply: 2 V ~ 5.5 V
• Embedded: No
• Utilized Ic / Part: LX1970
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Sensing Range: -
• Other names: LX1970MINI; LX1970MINI; LX1970MINIEVAL

Copyright © 2007
Rev. 1.5b, 2008-01-25
that resembles the human visual system. It is packaged in
clear MSOP package. Microsemi also offers the LX1971
with the same pin out and similar supply voltage range as
LX1970 light sensor.
however differs from that of the LX1970. In general the
LX1971 has lower sensitivity and a wider dynamic range.
proportional to the intensity of light falling on the photo
receptors. Although the gain varies depending on the
wavelength of the light and the direction of light, in general
for a 555nm wavelength (yellow-green), the sensitivity is:
light sensor is an integral part of a continuous lighting
control system.
application, the level of brightness of the backlight should
be adjusted in proportion to the level of ambient lighting;
the LX1970 can provide closed loop brightness control for
this type of system. For most indoor applications, the 1200
lux saturation point of the LX1970 is usually not a limiting
affect.
system must respond to external events that affect the
user’s ability to see clearly. For example, a sensor to turn
on headlights or a sensor to adjust the reflectivity of a rear
view mirrors. These systems require the sensor to have
dynamic range similar to sight. Like the human eye, the
square root function of the LX1971 makes it extra sensitive
to small changes at lower light levels. The wide dynamic
range allows the LX1971 to sense the difference between
twilight and daylight or sunshine and heavy cloud cover.
the LX1970 without load resistors based on the formula
above. It can be used as baseline guidelines to calculate
gain setting resistors. The compliance of the current source
output may result in premature saturation of the output
when load resistors are added.
voltage is specified typically at VDD-350mV @ about 100
lux. The second curve shows saturation of the output with
V
300uA the output becomes non-linear as it begins to
saturate.
IN
The LX1970 is a light sensor with a spectral response
The LX1970 has a responsiveness that is directly
The LX1970 is best suited for applications where the
The LX1971 is best suited for applications where the
The first curve shows the calculated responsiveness of
I
OUT
= 5V and a 10K resistor SRC to ground, above about
=
I N T E G R A T E D
L
×
. 0
76
For example, in an LCD backlighting
µ
A
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: [phone]
for L < 1200 lux
The LX1971 responsiveness
P R O D U C T S
The SRC compliance
A P P L I C A T I O N I N F O R M A T I O N
Analog Mixed Signal Group
Microsemi
1000
450
400
350
300
250
200
150
100
900
800
700
600
500
400
300
200
100
50
LX1970 Calculated SRC Full Range Response
0
LX1970 SRC Actual SRC with 10K Resistor
0
0
0
P
Visible Light Sensor
RODUCTION
200
200
400
400
Light (lux)
Light (lux)
D
600
600
ATA
S
800
800
HEET
1000
1000
1200
1200
LX1970
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