LX1973A
PRODUCTION DATA SHEET
Microsemi
Analog Mixed Signal Group
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 1
WWW.Microsemi .COM
Automotive Light Sensor
TM ®
Copyright © 2005
Rev. 1.2, 2009-05-26
DESCRIPTION
The LX1973A is a wide dynamic
range light sensor with a very low
dark current that is optimized for
sensing low level light signals that
typically occur under dark or
darkening outdoor ambient lighting.
The LX1973A has been optimized for
automotive systems such as headlamp
brightness control or rear view mirror
contrast control. Its radical (fractional
exponent) response when interfaced
with an 8 bit DAC can detect levels
down to 0.001 lux or levels as high as
500 lux.
The spectral response of the
integrated light sensor closely
emulates the human eye so it ignores
light such as infrared which emits
energy but doesn’t aid vision. This
eliminates the need for an Infrared
filter required with competitor’s light
sensors.
The LX1973A internal circuitry
consists of a diode array with
Microsemi’s Best Eye™ processing that
provides a nearly perfect photopic light
wavelength response curve. The sensor
output feeds into a wide dynamic range
compression amplifier that provides
accurate resolution over five decades of
ambient light. The integrated dark
current cancellation circuit facilitates
accurate sensing of light below 0.01
lux. The current source output of the
LX1973A can be gain scaled using one
external resistor.
The LX1973A is internally trimmed
to an initial accuracy of 5% at room
temperature and a light level of 10lux.
Accuracy of 10% is maintained over the
full temperature range (-40 to +85°C).
IMPORTANT: For the most current data, consult MICROSEMI’s website: http://www.microsemi.com
Protected By US Patents: 6,787,757; Patents Pending
KEY FEATURES
Nearly Perfect Best Eye™
Human Eye Spectral Response
25C Dark Current <0.005 lux
5 Decades Compressed Output
10% Accuracy Over
Temperature
Scalable Output Voltage
No Optical Filters Needed
APPLICATIONS
Auto headlamp control
Auto mirror contrast control
PRODUCT HIGHLIGHT
VOUT
5V
RLOAD
Part
LX1973A
LX1973A Response
0.0
1.0
2.0
3.0
4.0
0.001 0.01 0.1 1 10 100
Ambient Light (in lux)
Output (in Volts)
PACKAGE ORDER INFO
DR Plastic MSOP Reversed Form
8-Pin DU Plastic MSOP
8-pin
TA (°C)
RoHS Compliant / Pb-free RoHS Compliant / Pb-free
-40 to 85 LX1973AIDR LX1973AIDU
Note: Available in Tape & Reel. Append the letters “TR” to the part number. (i.e. LX1973AIDU-TR)
L
LX
X1
19
97
73
3A
A
LX1973A
PRODUCTION DATA SHEET
Microsemi
Analog Mixed Signal Group
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 2
WWW.Microsemi .COM
Automotive Light Sensor
TM ®
Copyright © 2005
Rev. 1.2, 2009-05-26
ABSOLUTE MAXIMUM RATINGS
VDD .................................................................................................................-0.3 to 6 VDC
SNK/SRC (Output Compliance Voltage)........................................... -0.3 to VDD + 0.3VDC
SNK/SRC (Maximum Output Current)...................................................Internally Limited
Operating Temperature Range........................................................................ -40 to +85°C
Storage Temperature Range.......................................................................... -40 to +100°C
RoHS / Pb-free Peak Package Solder Reflow Temperature
(40 seconds maximum exposure).................................................................... 260° (+0, -5)
Notes: Exceeding these ratings could cause damage to the device. All voltages are with respect to
Ground. Currents are positive into, negative out of specified terminal.
THERMAL DATA
DR Plastic MSOP 8-Pin Reverse Form
THERMAL RESISTANCE-JUNCTION TO CASE, θJC 39°C/W
THERMAL RESISTANCE-JUNCTION TO AMBIENT, θJA 206°C/W
DU Plastic MSOP 8-Pin
THERMAL RESISTANCE-JUNCTION TO CASE, θJC 39°C/W
THERMAL RESISTANCE-JUNCTION TO AMBIENT, θJA 206°C/W
Junction Temperature Calculation: TJ = TA + (PD x θJA).
The θJA numbers are guidelines for the thermal performance of the device/pc-board system. All of the
above assume no ambient airflow.
FUNCTIONAL PIN DESCRIPTION
Name Description
VDD Power Supply Voltage
VSS Ground Reference for Power and Signal Output
OUT Current Output
BP Internally Connected to Bonding Pad. This Pin Can Be Left Open or
Connected to VSS
NC No Connection Pin
PACKAGE PIN OUT
VDD
BP
NC
OUT
VSS
BP
NC
NC
DU PACKAGES
(Top View)
973A
YWWA
VDD
BP
NC
OUT
VSS
BP
NC
NC
PACKAGE MARKING
(Bottom View)
973A
YWWA
VDD
BP
NC
OUT
VSS
BP
NC
NC
PACKAGE MARKING
(Top View)
VDD
BP
NC
OUT
VSS
BP
NC
NC
DR PACKAGES
(Bottom View)
RoHS / Pb-free NiPdAu Finish
MSL 2/260°C/1 Year
SIMPLIFIED BLOCK DIAGRAM
VDD
VSS
OUT
Pre
Amplifier
Com-
pression
Amplifier
Photopic
Sensor with
Dark Current
Cancellation
Figure 1 – Simplified Block Diagram
P
PA
AC
CK
KA
AG
GE
E
D
DA
AT
TA
A
LX1973A
PRODUCTION DATA SHEET
Microsemi
Analog Mixed Signal Group
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 3
WWW.Microsemi .COM
Automotive Light Sensor
TM ®
Copyright © 2005
Rev. 1.2, 2009-05-26
ELECTRICAL CHARACTERISTICS
Unless otherwise specified, the following specifications apply over the operating ambient temperature -40°C≤ TA ≤ 85°C except where
otherwise noted and the following test conditions: See Note 1, VDD =5V.
LX1973A
Parameter Symbol Test Conditions Min Typ Max
Units
Operational Voltage VDD 4.5 5.5 V
Supply Current IDD EV = 1.0 lux 0.2 0.25 mA
Power Supply Rejection Ratio PSRR VRIPPLE = 100mVP-P, f = 10kHz; COUT = 0.1µF 30 35 dB
Peak Spectral Response λPR 580 nm
Infrared Response )(I
)(I
PRDD
DD
λ
λ EV(white) = 100 lux, EV(810nm) = 14.6µW/cm2,
Note 3 -5 1 5 %
Light to Current Gain GL See application section for equation
Saturation Current ISAT 570 µA
Radiant Sensitive Area 0.20 mm2
Flat Top Package (no t e 5)
Output Current IOUT(0.01) E
V = 0.01 lux @ 25°C, Note 1,2 32 36 40 µA
Output Current IOUT(1.0) E
V = 1.0 lux, Note 1,2 103 114 125 µA
Output Current IOUT(10) E
V = 10 lux, Note 1,2 183 203 223
Output Current IOUT(100) E
V = 100 lux, Note 1,2 320 360 400 µA
EV = 0 lux, TA = 20°C, Note 4 450 900
Dark Current (equivalent lux) IOUT (DARK) EV = 0 lux, TA = 50°C, Note 4 2100 5000
µLux
1.0 lux to 0.01 lux 1.5 3 sec
Dynamic Response Time
(to 10% settling error point) TDR 0.01 lux to 1.0 lux 0.2 0.5 sec
Reverse Form Package (note 6)
Output Current IOUT(0.01) E
V = 0.01 lux @ 25°C, Note 1,2 32 36 40 µA
Output Current IOUT(1.0) E
V = 1.0 lux, Note 1,2 105 117 128 µA
Output Current IOUT(10) E
V = 10 lux, Note 1,2, 187 208 229
Output Current IOUT(100) E
V = 100 lux, Note 1,2 333 370 407 µA
EV = 0 lux, TA = 20°C, Note 4 450 900 µLux
Dark Current (equivalent lux) IOUT (DARK) EV = 0 lux, TA = 50°C, Note 4 2100 5000
1.0 lux to 0.01 lux 1.5 3 sec
Dynamic Response Time
(to 10% settling error point) TDR 0.01 lux to 1.0 lux 0.2 0.5 sec
Notes:
1. The input irradiance is supplied from a point source which is a white light emitting diode (LED); Fairchild Semiconductor part number
MV8W00.
2. See Figure 2.
3. See Figure 3.
4. Dark Current equivalent lux at 0 lux: )10146( 9
4
−
×÷
⎥
⎦
⎤
⎢
⎣
⎡
=
REF
OUT
I
I
EL
5. For Flat Top (DU Package), IREF = 5824µA.
6. For Reverse Form (DR Package): IREF = 5985µA
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LX1973A
PRODUCTION DATA SHEET
Microsemi
Analog Mixed Signal Group
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 4
WWW.Microsemi .COM
Automotive Light Sensor
TM ®
Copyright © 2005
Rev. 1.2, 2009-05-26
TEST CIRCUITS
Part
White
LED
VDD
RLOAD
OUT
GND
VDD
VOUT
LX1973A
Figure 2 – Operational Voltage Measurement Circuit
White
LED 810nm
Part
VDD
RLOAD
OUT
GND
VDD
VOUT
LX1973A
Figure 3 – IR Sensitivity Measurement Circuit
APPLICATION CIRCUITS
5V
To µP
DAC/ADC
Part
LX1973A
10K 1µF
LX1800
Part
SCL
SCD
GND
ADR
VDD
AIN
REF
AOUT
5V
2.5V
LAMP
HEADLAMP
CONTROLLER
BRT
Figure 4 – Typical Application
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LX1973A
PRODUCTION DATA SHEET
Microsemi
Analog Mixed Signal Group
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 5
WWW.Microsemi .COM
Automotive Light Sensor
TM ®
Copyright © 2005
Rev. 1.2, 2009-05-26
APPLICATIONS
GENERAL DESCRIPTION
The LX1973A produces an output current that is sensitive to the level of ambient light that falls onto the
photosensitive area of the IC package. The sensitivity is amplified and compressed to provide ratio metric accuracy
across several decades. The sensitivity function is:
() ()
25.0
25.0 AMBIENTDARK
ref
OUT EE
lux
I
PI +×=
Iref = 113.8µA for the Flat Top package
Iref = 117µA for the Reverse Flat Top package
EDARK = dark current equivalent lux expressed in lux from a white LED point source.
EAMBIENT = ambient illumination expressed in lux from a white LED point sour ce.
A
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PP
PL
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TI
IO
ON
NS
S
LX1973A
PRODUCTION DATA SHEET
Microsemi
Analog Mixed Signal Group
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 6
WWW.Microsemi .COM
Automotive Light Sensor
TM ®
Copyright © 2005
Rev. 1.2, 2009-05-26
SENSITIVITY
DARK CURRENT VS TEMP
0
50
100
150
200
250
300
350
400
450
500
0.001 0.01 0.1 1 10 100 1000
Point Source Light (lux)
Output Current (µA)
100
1000
10000
100000
20 40 60 80 100
Temperature (C)
Dark Current (uLx)
NORMALIZED (PRE COMPRESSION)
100 LUX OUTPUT VOLTAGE (FLAT TOP)
-0.2
0.0
0.2
0.4
0.6
0.8
1.0
1.2
400 600 800 1000
Wavelength (nm)
Normalized Diode Response
LX1973A
Human Eye
0
1
2
3
4
5
6
02468101214
Load Re sistor (in kilo-ohms)
Output voltage
4.5V 5.0V 5.5V
IOUT STEP RESPONSE (FLAT TOP)
IOUT OVER TEMP @ 100 LUX, 10 LUX, 1 LUX
50
100
150
200
250
300
350
400
450
-50 -40 -10 25 50 85 100
Temperature ºC
IOUT (µA)
IOUT @ 100 Lux
IOUT @ 10 Lux
IOUT @ 1 Lux
Load = 10kΩ and 0µF; Photo Step = Direct Light Input of 1 lux to 0.01 lux.
C
CH
HA
AR
RT
TS
S
LX1973A
PRODUCTION DATA SHEET
Microsemi
Analog Mixed Signal Group
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 7
WWW.Microsemi .COM
Automotive Light Sensor
TM ®
Copyright © 2005
Rev. 1.2, 2009-05-26
PACKAGE DIMENSIONS
DU 8-Pin Miniature Shrink Outline Package (MSOP)
A1 L
E
L1
b
e
Ac
Top View
Side Views
PIN # NAME
1V
DD
2BP
3NC
4OUT
5NC
6NC
7BP
8V
SS
Ø
E
D
S
MILLIMETERS INCHES
Dim MIN MAX MIN MAX
A – 1.10 – 0.043
A1 0.05 0.15 0.002 0.006
b 0.26 0.41 0.010 0.016
c 0.13 0.23 0.005 0.009
D 2.90 3.10 0.114 0.122
e 0.65 BSC 0.025 BSC
E 4.75 5.05 0.187 0.198
E1 2.90 3.10 0.114 0.122
L 0.41 0.71 0.016 0.028
L1 0.95 BSC 0.037 BSC
S 0.525 BSC 0.021 BSC
Ø 3° 3°
DR 8-Pin Miniature Shrink Outline Package (MSOP) Reversed Form
E
A
0.12
E1
D
e
b
A1 cØ
L1
L
PIN # NAME
1V
DD
2BP
3NC
4OUT
5NC
6NC
7BP
8V
SS
S
MILLIMETERS INCHES
Dim MIN MAX MIN MAX
A – 1.10 – 0.043
A1 0.05 0.15 0.002 0.006
b 0.26 0.41 0.010 0.016
c 0.13 0.23 0.005 0.009
D 2.90 3.10 0.114 0.122
e 0.65 BSC 0.025 BSC
E 4.75 5.05 0.187 0.198
E1 2.90 3.10 0.114 0.122
L 0.41 0.71 0.016 0.028
L1 0.95 BSC 0.037 BSC
S 0.525 BSC 0.021 BSC
Ø 3° 3°
Note:
Dimensions do not include mold flash or protrusions;
these shall not exceed 0.155mm(.006”) on any side.
Lead dimension shall not include solder coverage.
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LX1973A
PRODUCTION DATA SHEET
Microsemi
Analog Mixed Signal Group
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 8
WWW.Microsemi .COM
Automotive Light Sensor
TM ®
Copyright © 2005
Rev. 1.2, 2009-05-26
PACKAGE INFORMATION
Package Land Pattern
1.02 mm ( 0.04 in.) 0.41 mm (0.016 in.)
0.65 mm (0.023 in.)
4.8 mm (0.189 in.)
VDD
BP
NC
OUT
VSS
BP
NC
NC
DU Package
1.02 mm ( 0.04 in.) 0.41 mm (0.016 in.)
0.65 mm (0.023 in.)
4.8 mm (0.189 in.)
VSS
BP
NC
NC
VDD
BP
NC
OUT
DR Package
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LX1973A
PRODUCTION DATA SHEET
Microsemi
Analog Mixed Signal Group
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 9
WWW.Microsemi .COM
Automotive Light Sensor
TM ®
Copyright © 2005
Rev. 1.2, 2009-05-26
PACKAGE TAPE AND REEL INFORMATION
4mm ±0.1
8mm ±0.1
5.5mm ±0.1
2mm ±0.1
12mm ±0.3
5.3mm ±0.1
Ø 1.55mm
±0.05
Ø 1.6mm
±0.1
REF
3.3mm ±0.1
3.3mm ±0.1
1.3mm ±0.1
1.0mm ±0.1
0.3mm ±0.05
0.15mm
Ref 0.4mm
Pin 1
DU Package Tape and Reel Information
4mm ±0.1
8mm ±0.1
5.5mm ±0.1
2mm ±0.1
12mm ±0.3
5.3mm ±0.1
Ø 1.55mm
±0.05
Ø 1.6mm
±0.1
REF
3.3mm ±0.1
3.3mm ±0.1
1.3mm ±0.1
1.0mm ±0.1
0.3mm ±0.05
0.15mm
Ref 0.4mm
Pin 1
DR Package Tape and Reel Information
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LX1973A
PRODUCTION DATA SHEET
Microsemi
Analog Mixed Signal Group
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 10
WWW.Microsemi .COM
Automotive Light Sensor
TM ®
Copyright © 2005
Rev. 1.2, 2009-05-26
NOTES
PRODUCTION DATA – Information contained in this document is proprietary to
Microsemi and is current as of publication date. This document may not be modified in
any way without the express written consent of Microsemi. Product processing does not
necessarily include testing of all parameters. Microsemi reserves the right to change the
configuration and performance of the product and to discontinue product at any time.
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