r
r
TSL2550
AMBIENT LIGHT SENSOR
WITH SMBus INTERFACE
TAOS029L
−
OCTOBER 2007
D
Converts Light Intensity to Digital Signal
D
Infrared Compensation to Approximate
Human Eye Response
PACKAGE D
8-LEAD SOIC
(TOP VIEW)
D
D
D
D
D
D
D
D
Companding A/D for Wide Dynamic Range
Rejects 50 Hz/60 Hz Lighting Ripple
Two-Wire SMBus Serial Interface
Single Supply Operation (2.7 V to 5.5 V)
Low Active Power (1 mW typ)
Power Down Mode
Low-Profile Surface-Mount Packages
RoHS Compliant
V
DD
1
NC 2
NC 3
GND 4
8 SMBData
7 NC
6 NC
5 SMBCLK
PACKAGE T
4-LEAD SMD
(TOP VIEW)
Description
The TSL2550 is a digital-output light sensor with
a two-wire, SMBus serial interface. It combines
two photodiodes and a companding analog-to-
digital converter (ADC) on a single CMOS
integrated circuit to provide light measurements
over an effective 12-bit dynamic range with a
response similar to that of the human eye.
V
DD
1
GND 2
4 SMBData
3 SMBCLK
The TSL2550 is designed for use with broad wavelength light sources. One of the photodiodes (channel 0) is
sensitive to visible and infrared light, while the second photodiode (channel 1) is sensitive primarily to infrared
light. An integrating ADC converts the photodiode currents to channel 0 and channel 1 digital outputs. Channel
1 digital output is used to compensate for the effect of the infrared component of ambient light on channel 0
digital output. The ADC digital outputs of the two channels are used to obtain a value that approximates the
human eye response in the commonly used unit of Lux.
This device is intended primarily for use in applications in which measurement of ambient light is used to control
display backlighting such as laptop computers, PDAs, camcorders, and GPS systems. Other applications
include contrast control in LED signs and displays, camera exposure control, lighting controls, etc. The
integrating conversion technique used by the TSL2550 effectively eliminates the effect of flicker from
AC-powered lamps, increasing the stability of the measurement.
Functional Block Diagram
Channel 0
Photodiode
Channel 1
Photodiode
V
DD
= 2.7 V to 5.5 V
Integrating
A/D Converter
Control Logic
Output Registers
SMBCLK
SMBData
Two-Wire Serial Interface
The
LUMENOLOGY
r
Company
Texas Advanced Optoelectronic Solutions Inc.
1001 Klein Road
S
Suite 300
S
Plano, TX 75074
S
(972) 673-0759
r
www.taosinc.com
1
r
Copyright
E
2007, TAOS Inc.
TSL2550
AMBIENT LIGHT SENSOR
WITH SMBus INTERFACE
TAOS029L
−
OCTOBER 2007
Terminal Functions
TERMINAL
NAME
GND
SMBCLK
SMBData
V
DD
D PKG
NO.
4
5
8
1
T PKG
NO.
2
3
4
1
I
I/O
TYPE
DESCRIPTION
Power supply ground. All voltages are referenced to GND.
SMBus serial clock input terminal — clock signal for SMBus serial data.
SMBus serial data I/O terminal — serial data I/O for SMBus.
Supply voltage.
Available Options
DEVICE
TSL2550
TSL2550
T
A
−40°C
to 85°
−40°C
to 85°
PACKAGE
−
LEADS
SOIC−8
T−4
PACKAGE DESIGNATOR
D
T
ORDERING NUMBER
TSL2550D
TSL2550T
Absolute Maximum Ratings over operating free-air temperature range (unless otherwise noted)
†
Supply voltage, V
DD
(see Note 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 V
Digital output voltage range, V
O
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
−0.3
V to +6 V
Digital output current, I
O
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
±
10 mA
SMBus input/output current, I
(SMBIN)
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
−1
mA to 20 mA
Operating free-air temperature range, T
A
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
−40°C
to 85°C
Storage temperature range, T
stg
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
−40°C
to 85°C
ESD tolerance, human body model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2000 V
Solder conditions in accordance with JEDEC J−STD−020A, maximum temperature (see Note 2) . . . 260°C
†
Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These are stress ratings only, and
functional operation of the device at these or any other conditions beyond those indicated under “recommended operating conditions” is not
implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
NOTES: 1. All voltage values are with respect to GND.
2.
Package D only:
The device may be hand soldered provided that heat is applied only to the solder pad and no contact is made
between the tip of the solder iron and the device lead. The maximum time heat should be applied to the device is 5 seconds.
Recommended Operating Conditions
MIN
Supply voltage, V
DD
Operating free-air temperature, T
A
SMBus input low voltage @ V
DD
= 3.3 V
±
5%, V
IL
SMBus input high voltage @ V
DD
= 3.3 V
±
5%, V
IH
SMBus operating frequency, f
(SMBCLK)
2.1
10
100
2.7
0
MAX
5.5
70
0.8
UNIT
V
°C
V
V
kHz
Copyright
E
2007, TAOS Inc.
r
r
The
LUMENOLOGY
r
Company
2
www.taosinc.com
TSL2550
AMBIENT LIGHT SENSOR
WITH SMBus INTERFACE
TAOS029L
−
OCTOBER 2007
Electrical Characteristics over recommended operating free-air temperature range (unless
otherwise noted)
PARAMETER
V
OL
SMBus output low voltage
I
O
= 50
μA
I
O
= 4 mA
Active, VSMBCLK and VSMDATA = V
DD,
V
DD
= 3.3 V
±
5%
Power down, VSMBCLK and VSMDATA =
V
DD,
V
DD
= 3.3 V
±
5%
VI = V
DD
VI = 0
0.35
TEST CONDITIONS
MIN
TYP
0.01
0.4
0.6
10
5
−5
MAX
UNIT
V
mA
μA
μA
μA
I
DD
I
IH
I
IL
Supply current
High level input current
Low level input current
Operating Characteristics, V
DD
= 3.3 V, T
A
= 255C (unless otherwise noted) (see Notes 2, 3, 4)
PARAMETER
TEST CONDITIONS
E
e
= 0
ADC count value standard mode
value,
λ
p
= 640 nm
E
e
= 72
μW/cm
2
λ
p
= 940 nm
E
e
= 140
μW/cm
2
E
e
= 0
ADC count value extended mode
value,
λ
p
= 640 nm
E
e
= 72
μW/cm
2
λ
p
= 940 nm
E
e
= 140
μW/cm
2
ADC count value ratio: Ch1/Ch0,
standard mode
λ
p
= 640 nm, E
e
= 72
μW/cm
2
λ
p
= 940 nm, E
e
= 140
λ
p
= 640 nm
E
e
= 72
μW/cm
2
λ
p
= 940 nm
E
e
= 140
μW/cm
2
Fluorescent light source: 300 Lux
R
v
Illuminance responsivity standard mode
responsivity,
Incandescent light source: 50 Lux
(Sensor Lux) / (actual Lux), standard mode
(Note 5)
Fluorescent light source: 300 Lux
Incandescent light source: 50 Lux
μW/cm
2
Ch0
Ch1
Ch0
Ch1
Ch0
Ch1
Ch0
Ch1
0.65
0.5
CHANNEL
Ch0
Ch1
Ch0
Ch1
Ch0
Ch1
Ch0
Ch1
Ch0
Ch1
Ch0
Ch1
0.070
0.70
155
16
155
139
0.106
0.88
11.1
1.2
5.7
5
2.8
0.23
19
13
1
1
1.35
1.5
counts/
lux
counts/
(μW/
cm
2
)
0.175
1.20
511
639
799
85
799
703
1
1
counts
1039
MIN
TYP
MAX
1
1
959
counts
UNIT
R
e
Irradiance responsivity standard mode
responsivity,
NOTES: 3. Optical measurements are made using small-angle incident radiation from light-emitting diode optical sources. Visible 640 nm LEDs
and infrared 940 nm LEDs are used for final product testing for compatibility with high volume production.
4. The 640 nm irradiance E
e
is supplied by an AlInGaP light-emitting diode with the following characteristics: peak wavelength
λp
= 640 nm and spectral halfwidth
Δλ½
= 17 nm.
5. The 940 nm irradiance E
e
is supplied by a GaAs light-emitting diode with the following characteristics: peak wavelength
λp
= 940 nm and spectral halfwidth
Δλ½
= 40 nm.
6. The sensor Lux is calculated using the empirical formula shown on p. 11 of this data sheet based on measured Ch0 and Ch1 ADC
count values for the light source specified. Actual Lux is obtained with a commercial luxmeter. The range of the (sensor Lux) / (actual
Lux) ratio is estimated based on the variation of the 640 nm and 940 nm optical parameters. Devices are not 100% tested with
fluorescent or incandescent light sources.
The
LUMENOLOGY
r
Company
r
r
Copyright
E
2007, TAOS Inc.
www.taosinc.com
3
TSL2550
AMBIENT LIGHT SENSOR
WITH SMBus INTERFACE
TAOS029L
−
OCTOBER 2007
AC Electrical Characteristics, V
DD
= 3.3 V, T
A
= 255C (unless otherwise noted)
PARAMETER
t
(CONV)
t
(CONV)
f
(SMBCLK)
t
(BUF)
t
(HDSTA)
t
(SUSTA)
t
(SUSTO)
t
(HDDAT)
t
(SUDAT)
t
(LOW)
t
(HIGH)
t
(TIMEOUT)
t
F
t
R
C
i
Conversion time, per channel, standard mode
Conversion time, per channel, extended mode
Clock frequency
Bus free time between start and stop condition
Hold time after (repeated) start condition. After
this period, the first clock is generated.
Repeated start condition setup time
Stop condition setup time
Data hold time
Data setup time
SMBCLK clock low period
SMBCLK clock high period
Detect clock/data low timeout
Clock/data fall time
Clock/data rise time
Input pin capacitance
4.7
4
4.7
4
300
250
4.7
4
25
35
300
1000
10
TEST CONDITIONS
MIN
TYP
400
80
100
MAX
UNIT
ms
ms
kHz
μs
μs
μs
μs
ns
ns
μs
μs
ms
ns
ns
pF
Copyright
E
2007, TAOS Inc.
r
r
The
LUMENOLOGY
r
Company
4
www.taosinc.com
TSL2550
AMBIENT LIGHT SENSOR
WITH SMBus INTERFACE
TAOS029L
−
OCTOBER 2007
PARAMETER MEASUREMENT INFORMATION
t
(LOW)
t
(R)
t
(F)
SMBCLK
V
IH
V
IL
t
(HDSTA)
t
(BUF)
t
(HDDAT)
V
IH
V
IL
t
(HIGH)
t
(SUSTA)
t
(SUDAT)
t
(SUSTO)
SMBDATA
P
Stop
Condition
S
Start
Condition
Start
S
Stop
t
(LOWSEXT)
SMBCLK
ACK
SMBCLK
ACK
t
(LOWMEXT)
t
(LOWMEXT)
t
(LOWMEXT)
P
SMBCLK
SMBDATA
Figure 1. SMBus Timing Diagrams
1
SMBCLK
9
1
9
SMBDATA
Start by
Master
A6
A5
A4
A3
A2
A1
A0
R/W
ACK by
TSL2550
D7
D6
D5
D4
D3
D2
D1
D0
ACK by Stop by
TSL2550 Master
Frame 1 SMBus Slave Address Byte
Frame 2 Command Byte
Figure 2. SMBus Timing Diagram for Send Byte Format
1
SMBCLK
9
1
9
SMBDATA
Start by
Master
A6
A5
A4
A3
A2
A1
A0
R/W
ACK by
TSL2550
D7
D6
D5
D4
D3
D2
D1
D0
NACK by Stop by
Master Master
Frame 1 SMBus Slave Address Byte
Frame 2 Data Byte From TSL2550
Figure 3. SMBus Timing Diagram for Receive Byte Format
The
LUMENOLOGY
r
Company
r
r
Copyright
E
2007, TAOS Inc.
www.taosinc.com
5
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