LX1973B
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 © 2007
Rev. 1.3, 2008-01-11
L
LX
X1
19
97
73
3B
B
DESCRIPTION
The LX1973B 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 LX1973B 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 LX1973B 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
LX1973B can be gain scaled using one
external resistor.
The LX1973B is internally trimmed
to an initial accuracy of 5% at room
temperature and a light level of 10 Lux.
Accuracy of 10% is maintained over the
full temperature range (-40 to +85ºC).
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
Dark Current < 0.0005 Lux (@
25°C)
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
5V
VOUT
Part
LX1973B
RLOAD
LX 1973B R esponse
0
1
2
3
4
0.001 0.01 0.1 1 10 100
Am bient Light (lux)
Output (volts)
PACKAGE ORDER INFO
PL
Plastic MSOP Domed
8-Pin PR
Plastic MSOP Domed
8-Pin Reverse Form
TA (°C) RoHS Compliant / Pb-free, NiPdAu Finish RoHS Compliant / Pb-free, NiPdAu Finish
-40 to 85 LX1973BIPL LX1973BIPR
Note: Available in Tape & Reel. Append the letters “TR” to the part number. (i.e. LX1973BIPL-
xxxxx-TR)
LX1973B
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 © 2007
Rev. 1.3, 2008-01-11
L
LX
X1
19
97
73
3B
B
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)..................................................................240°C (+0, -5)
Notes:
1. 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
PL Plastic MSOP Domed 8-Pin
PR Plastic MSOP Domed 8-Pin Reverse Form
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 Pin Description
VDD 1 Power Supply Voltage
VSS 8 Ground Reference for Power and Signal Output
OUT 4 Output Current
PACKAGE PIN OUT
VDD
NC
NC
OUT
VSS
NC
NC
NC
PL PACKAGES
(Top View)
973B
YWWB
VSS VDD
NC
OUT
NC
NC
NC
NC
PL PACKAGE MARKING
(Bottom View)
973B
YWWB
VSS VDD
NC
OUT
NC
NC
NC
NC
PR PACKAGE MARKING
(Top View)
VDD
NC
NC
OUT
VSS
NC
NC
NC
PR PACKAGES
(Bottom View)
NC – No Connection
MSL3/240°C/168 Hours
SIMPLIFIED BLOCK DIAGRAM
PACKAGE
VDD
OUT
Photopic
S e n s o r w ith
Dark Current
Cancellation
P re A mplifier Com pression
Amplifier
GND
LX1973B
Figure 1 – Simplified Block Diagram
LX1973BIPL
LX1973BIPR
LX1973B
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 © 2007
Rev. 1.3, 2008-01-11
L
LX
X1
19
97
73
3B
B
ELECTRICAL CHARACTERISTICS
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, ROUT = 10k.
LX1973B
Parameter Symbol Test Conditions Min Typ Max Units
Operational Voltage VDD 4.5 5.5 V
Supply Current IDD @ 1 Lux 0.22 0.27 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
DDλ
λ EV(white) = 100 Lux, EV(810nm) = 14.6µWatt/ cm²,
Note 3 -5 1 5 %
Light to Current Gain GL See application section for equation
Saturation Current ISAT 520 µA
1.0 Lux to 0.01 Lux 0.63 1.25 sec
Dynamic Response Time
(to 10% Settling Error Point) TDR 0.01 Lux to 1.0 Lux 0.2 0.5 sec
` Dome Top Package
Output Current IOUT(0.01) E
V = 0.01 Lux @ 25°C, Note 1,2 36 40 44 µA
Output Current IOUT(1.0) E
V = 1.0 Lux, Note 1,2 114 126 139 µA
Output Current IOUT(10) E
V = 10 Lux, Note 1,2 202 224 246 µA
Output Current IOUT(100) E
V = 100 Lux, Note 1,2 369 410 451 µA
EV = 0 Lux, TA = 20°C, Note 4 190 380
Dark Current (Equivalent Lux) IOUT (DARK) EV = 0 Lux, TA = 50°C, Note 4 700 1400
µLux
` Dome Bottom Package
Output Current IOUT(0.01) E
V = 0.01 Lux @ 25°C, Note 1,2 36 40 44 µA
Output Current IOUT(1.0) E
V = 1.0 Lux, Note 1,2 112 124 137 µA
Output Current IOUT(10) E
V = 10 Lux, Note 1,2 201 223 245 µA
Output Current IOUT(100) E
V = 100 Lux, Note 1,2 365 405 445 µA
EV = 0 Lux, TA = 20°C, Note 4 190 380
Dark Current (Equivalent Lux) IOUT (DARK) EV = 0 Lux, TA = 50°C, Note 4 700 1400
µLux
Notes:
1. The input irradiance is supplied from a point source which is a white light emitting diode (LED); Fairchild Semiconductor p art number
MV8W00.
2. See Figure 2.
3. See Figure 3.
4. Dark Current equivalent Lux at 0 Lux: )10(146
I
I
EL 9
4
REF
OUT −
×÷
⎥
⎦
⎤
⎢
⎣
⎡
=
For Dome Top Package, IREF = 6446µA.
For Dome Bottom Package, IREF= 6344µA.
E
EL
LE
EC
CT
TR
RI
IC
CA
AL
LS
S
LX1973B
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 © 2007
Rev. 1.3, 2008-01-11
L
LX
X1
19
97
73
3B
B
TEST CIRCUITS
Part
LX1973B
OUT
GND
VDD
White
LED RLOAD
VOUT
VDD
Figure 2 – Operational Voltage Measurement Circuit
Part
LX1973B
OUT
GND
VDD
White
LED RLOAD
VOUT
VDD
810nm
Figure 3 – IR Sensitivity Measurement Circuit
APPLICATION CIRCUITS
Part
SCL
SCD
GND
ADR
VDD
REF
AIN
AOUT
LX1800
DAC / ADC
Part
5V
2.5V
Headlamp
Controller
BRT
10K 1µF
5V
LX1973B
Lamp HI
Figure 4 – Typical Application
LX1973B
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 © 2007
Rev. 1.3, 2008-01-11
L
LX
X1
19
97
73
3B
B
APPLICATIONS
GENERAL DESCRIPTION
The LX1973B 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:
()
[]
0.25
EE
0.25
Lux1
I
PI AMBIENTDARK
ref
OUT +×=
1 Lux 0.25 = 10.25
Iref = 126µA for the Domed Top Package
Iref = 124µA for the Domed Bottom 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 source.
LX1973B
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 © 2007
Rev. 1.3, 2008-01-11
L
LX
X1
19
97
73
3B
B
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
Temp erat ure (C)
Dark Current (µLux)
NORMALIZED (PRE COMPRESSION)
100 LUX OUTPUT VOLTAGE
-0.2
0.0
0.2
0.4
0.6
0.8
1.0
1.2
400 600 800 1000
Wavelength (nm)
LX1973B
Human Eye
Normalized Diode Response
0
1
2
3
4
5
6
02468101214
Load Resistor (in kilo-ohms)
Output Voltage
4.5V
5.0V
5.5V
IOUT VS TEMPERATURE & VDD
IOUT STEP RESPONSE
Iout vs Temperature @ 10 lux
195
205
215
225
-40 -20 0 20 40 60 80 100
Temperature (ºC )
Iout (uA)
Iout @ 4.5V
Iout @ 5.0V
Iout @ 5.5V
Load =10k and 0µF;
Photo Step = Direct Light Input of 1 Lux to 0.01 Lux.
LX1973B
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 © 2007
Rev. 1.3, 2008-01-11
L
LX
X1
19
97
73
3B
B
PACKAGE DIMENSIONS
PL 8-Pin Miniature Shrink Outline Package (MSOP) Dome Top
D
E
e
E/2
D/2
A2
L1
L
b
A1 Seating Plane
E1
c
A
S
θ
R 0.9mm
Typ
1234
5678
PIN # NAME
1V
DD
2NC
3NC
4OUT
5NC
6NC
7NC
8V
SS
MILLIMETERS INCHES
Dim MIN MAX MIN MAX
A 1.60 1.85 0.063 0.073
A1 0.05 0.15 0.002 0.006
A2 - 1.10 - 0.043
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 4.75 5.05 0.187 0.199
E1 2.90 3.10 0.114 0.122
e 0.65 BSC 0.026 BSC
L 0.41 0.71 0.016 0.028
L1 0.95 REF 0.037 REF
S 0.525 REF 0.021 REF
θ 3° 3°
Note:
1. Dimensions do not include mold flash or
protrusions; these shall not exceed
0.155mm(.006”) on any si de. Lead d imensio n
shall not include solder coverage.
PR 8-Pin Plastic MSOP Clear Package Inverted Dome
E
A
E1
D
e1
e
b
A2
A3 A1 c
θ
L1
L
PIN # NAME
1V
DD
2NC
3NC
4OUT
5NC
6NC
7NC
8V
SS
1234
5678
MILLIMETERS INCHES
Dim MIN MAX MIN MAX
A - 1.68 - 0.066
A1 0.05 0.15 0.002 0.006
A2 0.81 0.92 0.032 0.036
A3 0.66 0.76 0.026 0.030
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 4.75 5.05 0.187 0.199
E1 2.90 3.10 0.114 0.122
e 0.65 BSC 0.026 BSC
e1 1.95 TYP 0.077 TYP
L 0.41 0.71 0.016 0.028
L1 0.95 REF 0.037 REF
θ 5° 5°
LX1973B
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 © 2007
Rev. 1.3, 2008-01-11
L
LX
X1
19
97
73
3B
B
PACKAGE DIMENSIONS (CONTINUED)
Light Footprint
Active Area
Required Mi ni m um Li ght footpri
Bonding / Wafer area
Recommended light footprint pattern
P2
L
C
Recommended
light foot print
P1
Minimum light
foot print
Dome Top Package
Dim MILLIMETERS INCHES
P1 1.8 0.070
P2 2.5 0.098
Note:
P2 represents a possible light footprint and its
dimensions are not subject to strict tolerances.
Only P1 is required to be covered with light. This
larger footprint is designed to ensure coverage of
the device’s active area.
Active Ar ea
Required M inimum Light footprint
Bonding / Wafer area
Recommended light footprint pattern
P2
L
C
Recommended
light foot print
P1
Recommended
PCB Cutout
Minimum light
foot print
P3
Dome Bottom Package
Dim MILLIMETERS INCHES
P1 1.8 0.070
P2 2.5 0.098
P3 2.9 0.114
Note:
P2 represents a possible light footprint and its
dimensions are not subject to strict tolerances. Only
P1 is required to be covered with light. This larger
footprint is designed to ensure coverage of the
device’s active area.
P3 represents the minimum aperture through which
the dome of the device would fit in the PCB.
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.
