LS521
Version
Issue Date
File Name
Total Pages
: A.002
: 2015/07/10
: SP-LS521-A.002.doc
: 12
ILLUMINATION-TO-DIGITAL CONVERTER
with SMBUS INTERFACE
新竹市科學園區展業一路 9 號 7 樓之 1
SILICON TOUCH TECHNOLOGY INC.
9-7F-1, Prosperity Road I, Science Based Industrial Park,
Hsin-Chu, Taiwan 300, R.O.C.
Tel：886-3-5645656
Fax：886-3-5645626
點晶科技股份有限公司
LS521
SILICON TOUCH TECHNOLOGY INC.
ILLUMINATION-TO-DIGITAL CONVERTERS
GENERAL DESCRIPTION
The LS521 is a low-noise, high-sensitivity and illumination-to-digital converter with two-wire SMBus serial
interface. The device integrates a photodiode, a trans-impedance amplifier, and 8-bits analog-to-digital converter
(ADC) in a single IC to provide illumination information over an effective 8-bit dynamic range. The digital
output is directly proportional to ambient illumination. The LS521 is characterized with the C.I.E. response as the
human eye’s visual response, which peaks at 555nm.
Illumination information can be used to control display panel backlighting with the purpose of extending
battery life and providing optimum viewing in diverse lighting conditions. Also, illumination information can
further be used to manage exposure control in digital cameras and camcorders. The LS521 device is ideal in
notebook/tablet PCs, flat-panel televisions, cellular phones, LCD monitors, digital cameras, camcorder, and
street/room lighting control, etc.
FEATURES
1.
Characterized with the C.I.E. response as the human eye’s response
2.
8-bit linear digital output for ambient illumination with two wire SMBus interface.
3.
Tunable illumination sensitivity by an external resistor
4.
Rejection of 50Hz/60Hz light ripple by an external resistor (RL) and an external capacitor (CL)
5.
Wide power supply range (2.7~5.5V)
6.
Low power dissipation in shut-down mode.
7.
Tiny SMD type package:
Width: 3.0mm/Height: 3.0 mm/Depth: 1.1mm
Width: 2.0mm/Height: 2.0 mm/Depth: 0.63mm
8.
High sensing illuminance range (0~14000 lux).
ILLUMINATION-TO-DIGITAL CONVERTER with SMBUS INTERFACE
Version：A.002
Page1
點晶科技股份有限公司
LS521
SILICON TOUCH TECHNOLOGY INC.
FUNCTIONAL BLOCK DIAGRAM and APPLICATION
VDD
0.1uF
Oscillator
CL
RL
A/D converter
Command Register
SMBus Interface
Control
Logic
REXT
ADC Register
VSS
SCL
K
SDA
ABSOLUTE MAXIMUM RATINGS
Item
Supply Voltage
Input Voltage for SCLK, SDA, REXT
Input Current for SCLK, SDA
Output Current for SDA
Operating Temperature
Storage Temperature
Electrostatic Damage, (HBM)
Symbol
VDD
VIN
IIN
IOUT
Topr
Tstg
ESD
Ratings
-0.4 ~ 6
-0.4 ~ VDD+0.4
+20
-1
-25 to +85
-40 to +125
3
Unit
V
mA
mA
mA
℃
℃
kV
RECOMMENDED OPERATING CONDITIONS
Item
Supply Voltage
Operating Temperature
Input Low Voltage for SCLK, SDA
Input High Voltage for SCLK, SDA
Operating Frequency for SCLK
Symbol
VDD
Topr
VIL
VIH
fSCLK
Min.
2.7
-25
2.1
10
ILLUMINATION-TO-DIGITAL CONVERTER with SMBUS INTERFACE
Typ.
Max.
5.5
85
0.8
VDD
400
Unit
V
℃
V
V
KHz
Version：A.002
Page2
點晶科技股份有限公司
LS521
SILICON TOUCH TECHNOLOGY INC.
ELECTRICAL CHARACTERISTICS (VDD=3V, TA=25℃ if not mentioned )
Item
Symbol
SMBus Output Low Voltage
VOL
Supply Current
Test Conditions
Min.
Typ.
Max.
Unit
IO =10uA
-
0.01
-
V
IO =350uA
-
-
0.4
V
-
0.38
0.43
-
0.65
0.75
-
30
35
-
80
92
-
0.33
0.38
-
0.6
0.7
VDD
Power-up,
=3V
VSMBCLK =VSMBDAT=VDD, Ee =0, VDD
=5.5V
VDD
Power-down,
=3V
VSMBCLK=VSMBDAT = VDD, Ee =0 VDD
=5.5V
VDD
Shut-down ADC,
=3V
VSMBCLK=VSMBDAT =VDD, Ee =0 VDD
=5.5V
IDD
mA
uA
mA
High Level Input Current
IIH
VSDA(or VSCL)=VDD
-
-
5
uA
Low Level Input Current
IIL
VSDA(or VSCL)= 0V
-
-
-5
uA
DC OPERATING CHARACTERISTICS (VDD=3V, TA=25℃, RL=11.9kΩ, CL=100uF, unless
otherwise noted)
Item
Symbol
Test Conditions
Min.
Typ.
Max.
Unit
Full scale ADC count
-
-
-
-
255
counts
-
0
2
83
104
125
0.208
0.26
0.312
Ee =0
ADC count value
Illuminance responsivity
DOUT
Rv
counts
Ee =400 lux,
Fluorescent light
(note.1)
Fluorescent light
(note.1)
counts/
lux
NOTE: 1. Using a white LED as the fluorescent light source.
MAXIMUM ILLUMINANCE RANGE SETTING
ILLUMINATION-TO-DIGITAL CONVERTER with SMBUS INTERFACE
Version：A.002
Page3
點晶科技股份有限公司
LS521
SILICON TOUCH TECHNOLOGY INC.
Max. illuminance range(LUX)
RL(KΩ )
1000
2000
5000
14000
12
6
2.4
0.857
Table 1. Maximum illuminance range vs R L
For example, if we need the maximum illuminance range to be 2000 lux, then
RL 
1200
 6( K)
0.1 2000
where 1200 and 0.1 are constants, 2000 is max. lux
REJECTION OF LIGHT RIPPLE
Cut off frequency(Hz)
RL (kΩ )
CL (uF)
Table 2.
60
6
0.45
1
2.4
1.2
6
27
2.4
67
RL , CL setting
For example, if light ripple(f)=60Hz, RL=6kΩ , then
CL 
1
1

 0.4421(uF )
2R  f 2  6000  60
AC OPERATING CHARACTERISTICS (VDD=3V, TA=25℃ unless otherwise noted)
Item
Symbol
Min.
Typ.
Max.
Unit
kHz
Clock frequency
f(SMBCLK)
10
-
400
Bus free time between start and stop condition
Hold time after (repeated) start condition. After this
period, the first clock is generated.
t(BUF)
4.7
-
-
us
t(HDSTA)
4
-
-
us
Repeated start condition setup time
t(SUSTA)
4.7
-
-
us
Stop condition setup time
t(SUSTO)
4
-
-
us
Data hold time
t(HDDAT)
300
-
-
ns
Data setup time
t(SUDAT)
250
-
-
ns
SMBCLK clock low period
t(LOW)
4.7
-
-
us
SMBCLK clock high period
t(HIGH)
4
-
50
us
Detect clock low timeout
t(TIMEOUT)
25
-
35
ms
Clock/data fall time
tF
-
-
300
ns
Clock/data rise time
tR
-
-
1000
ns
Input pin capacitance
Ci
-
-
10
pF
PARAMETER MEASUREMENT INFORMATION
ILLUMINATION-TO-DIGITAL CONVERTER with SMBUS INTERFACE
Version：A.002
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點晶科技股份有限公司
LS521
SILICON TOUCH TECHNOLOGY INC.
SMBUS TIMING DIAGRAM
ILLUMINATION-TO-DIGITAL CONVERTER with SMBUS INTERFACE
Version：A.002
Page5
點晶科技股份有限公司
LS521
SILICON TOUCH TECHNOLOGY INC.
SLAVE ADDRESS SELECTION
Address
Description
0010000
Address of LS521.
COMMAND SELECTION
Command
0x00h
0x01h
0x02h
0x80h
Description
Power-up mode/Read Data Register
Power-down mode
Shut down ADC
Read Command Register
SMBUS PROTOCOLS(For more detail about SMBUS protocols, please refer to the website
http://www.smbus.org/specs/ )
Figure 4. SMBUS packet protocol diagram element key
ILLUMINATION-TO-DIGITAL CONVERTER with SMBUS INTERFACE
Version：A.002
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點晶科技股份有限公司
LS521
SILICON TOUCH TECHNOLOGY INC.
Figure 5. SMBUS send byte protocol
Figure 6. SMBUS receive byte protocol
Figure 7. SMBUS read byte protocol
Figure 8. SMBUS read word protocol
ILLUMINATION-TO-DIGITAL CONVERTER with SMBUS INTERFACE
Version：A.002
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點晶科技股份有限公司
LS521
SILICON TOUCH TECHNOLOGY INC.
Spectral response
LIGHT TO DIGITAL@VDD=3V
(fluorescent light)
1.2
relative responsivity
280
Digital output(counts)
240
200
RL=1.2KΩ
RL=6KΩ
160
120
80
40
0.8
0.6
0.4
0.2
0
0
2000
4000
6000
8000
10000
LS521
CIE
1.0
0.0
12000 14000
300
Ambient light(lux)
500
700
900
1100
wavelength(nm)
Digital variation
Temperature variation@VDD=3V
60
60
50
40
Digital output
Digital output
50
Ee=800lux(flourescent),
R=1.2KΩ
30
20
Ee=500lux(flourescent), R=1.2KΩ
40
Ee=0lux, R=1.2KΩ
30
20
10
0
10
-10
0
-40 -30 -20 -10
2
3
4
VDD(volt)
5
IDD vs Temp.@Ee=0lux
TOP view
1.0
3V
Y
X
5V
IDD(mA)
Digital output
10 20 30 40 50 60 70 80 90
Temperature(℃)
Incident angle vs Responsivity@VDD=3V
fluorescent light Ee=500lux
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
0
6
0.5
0.0
-90 -80 -70 -60 -50 -40 -30 -20 -10 0
10 20 30 40 50 60 70 80 90
-40 -30 -20 -10 0
Incident angle
ILLUMINATION-TO-DIGITAL CONVERTER with SMBUS INTERFACE
10 20 30 40 50 60 70 80 90
Temperature(℃)
Version：A.002
Page8
點晶科技股份有限公司
LS521
SILICON TOUCH TECHNOLOGY INC.
PACKAGE DESCRIPTIONS

IPLCC8
●
Top View
3mm x 3mm x 1.1mm
●
Bottom View
PAD DESCRIPTIONS
PIN NO.
PIN NAME
DESCRIPTIONS
1
2
3
SCL
VDD
VSS
Serial Clock IN
Power
Ground
4
5
6
7
8
---
---
SDA
Serial Data I/O
ILLUMINATION-TO-DIGITAL CONVERTER with SMBUS INTERFACE
--
--
Rext
External Resistor
Version：A.002
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點晶科技股份有限公司
LS521
SILICON TOUCH TECHNOLOGY INC.

IPLCC6
2mm x 2mm x 0.63mm
ILLUMINATION-TO-DIGITAL CONVERTER with SMBUS INTERFACE
Version：A.002
Page10
點晶科技股份有限公司
LS521
SILICON TOUCH TECHNOLOGY INC.
REFLOW SOLDERING
The products listed herein are designed for ordinary electronic applications, such as
electrical appliances, audio-visual equipment, communications devices and so on. Hence,
it is advisable that the devices should not be used in medical instruments, surgical
implants, aerospace machinery, nuclear power control systems, disaster/crime-prevention
equipment and the like. Misusing those products may directly or indirectly endanger
human life, or cause injury and property loss.
Silicon Touch Technology, Inc. will not take any responsibilities regarding the misusage
of the products mentioned above. Anyone who purchases any products described herein
with the above-mentioned intention or with such misused applications should accept full
responsibility and indemnify. Silicon Touch Technology, Inc. and its distributors and all
their officers and employees shall defend jointly and severally against any and all claims
and litigation and all damages, cost and expenses associated with such intention and
manipulation.
ILLUMINATION-TO-DIGITAL CONVERTER with SMBUS INTERFACE
Version：A.002
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