Analogic AAT3114ISN-20-T1 High efficiency 1.5x fractional charge pumps for white led application Datasheet

AAT3113/4
High Efficiency 1.5X Fractional Charge
Pumps For White LED Applications
General Description
Features
The AAT3113/4 are low noise, constant frequency
charge pump DC/DC converters that use fractional
(1.5X) conversion to increase efficiency in White
LED applications. The devices can be used to produce current levels up to 20mA for each output from
a 2.7V to 5.5V input. Low external parts counts (two
1µF flying capacitors and two small bypass capacitors at VIN, and OUT) make the AAT3113/4 ideally
suited for small battery-power applications.
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AnalogicTech™’s Simple Serial Control™
(S2Cwire™) interface is used to enable, disable
and set the LED drive current for a 32 level logarithmic scale LED brightness control. The
AAT3113/4 have a thermal management system to
protect the device in the event of a short circuit
condition on any of the output pins. Built-in softstart circuitry prevents excessive inrush current
during start-up. High switching frequency enables
the use of small external capacitors. A low current
shutdown feature disconnects the load from VIN
and reduces quiescent current to less than 1µA.
The AAT3113 provides 4 LED current source outputs, and the AAT3114 provides 6. The AAT3113/4
are available in 16-pin quad QFN packages, and
the AAT3113 is also available in the 12-pin
TSOPJW package.
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•
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•
ChargePump™
White LED Backlighting
AAT3113 - 4 Outputs
AAT3114 - 6 Outputs
20mA Full Scale Current
32 Position Logarithmic Scale with Digital
Control
Simple Serial Control™ (S2Cwire™) interface
Low Noise Constant Frequency Operation
33% Less Input Current Than Doubler
Charge Pump
High Accuracy Brightness Matching
Small Application Circuit
Regulated Output Current
Automatic Soft-Start
VIN Range: 2.7V to 5.5V
No Inductors
600kHz Switching Frequency
Iq < 1µA in Shutdown
Temperature Range -40 to 85°C.
16-Pin QFN, 12-Pin TSOPJW Package
Applications
•
•
White LED Backlighting
Programmable Current Source
Typical Application
VIN
C1+
C1
1µF
C1C2+
VOUT
VBATTERY
CIN
1µF
COUT
1µF
AAT3114
C2
1µF
C2-
EN/SET
EN/SET
GND
D1
D2
D3
D4
D5
D6
D6
3113.2004.07.1.4
D5
D4
D3
D2
D1
1
AAT3113/4
High Efficiency 1.5X Fractional Charge
Pumps For White LED Applications
Pin Descriptions
Pin #
QFN44-16
TSOPJW-12
Symbol
Function
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
7
6
5
N/A
N/A
4
3
N/A
2
1
12
11
N/A
10
9
8
D2
D3
D4
D5
D6
C1+
C1NC
OUT
C2+
C2GND
NC
VIN
EN/SET
D1
Current source output
Current source output
Current source output
Current source output (3114 option only)
Current source output (3114 option only)
Flying Capacitor 1 + terminal
Flying Capacitor 1 - terminal
No Connect
Charge pump output. Requires 1uF bypass capacitor to ground.
Flying Capacitor 2 + terminal
Flying Capacitor 2 - terminal
Ground
No Connect
Input power supply. Requires 1uF bypass capacitor to ground.
Control Pin using S2Cwire serial interface.
Current source output 1. Required reference current source.
Part Number Descriptions
Part Number
AAT3113-20
AAT3114-20
Function
4 Diode outputs, 20mA full scale
6 Diode outputs, 20mA full scale
Pin Configuration
12-Lead TSOPJW
(Top View)
5
8
6
7
D3
2
D4
3
(D5)
4
AAT3113/4
12
GND
11
C2-
10
C2+
9
OUT
8
7
6
5
NC
C1-
C1+
(D6)
2
13
9
1
14
10
4
D2
NC
VIN
3
C2GND
VIN
EN/SET
D
D
15
11
EN/SET
12
2
16
1
D1
C2+
OUT
C1C1+
D
D
16 LD 4x4mm QFN
(Top View)
3113.2004.07.1.4
AAT3113/4
High Efficiency 1.5X Fractional Charge
Pumps For White LED Applications
Absolute Maximum Ratings
Symbol
VIN
VOUT
VEN/SET
VEN/SET(MAX)
IOUT
θJA
TJ
(TA=25°C unless otherwise noted)
Description
Input Voltage
Charge Pump Output
EN/SET to GND Voltage
Maximum EN/SET to Input Voltage
Maximum DC Output Current (Sum of Iout and D currents)
Thermal Resistance
Operating Junction Temperature Range
Value
Units
-0.3 to 6
-0.3 to 6
-0.3 to 6
0.3
150
37
-40 to 150
V
V
V
V
mA
°C/W
°C
Electrical Characteristics
VIN=3.5V, TA = -40 to 85°C unless otherwise noted. Typical values are at TA = 25°C.
Symbol
Description
Input Power Supply
VIN
Operation Range
ICC
Operating Current
ISHDN
Shutdown Current
IDX
∆ID/∆VIN
I(D-Match)
η
Charge Pump
tSS
FCLK
EN/SET
VEN(L)
VEN(H)
tLO
tHI
tOFF
Input Current
3113.2004.07.1.4
Output Current
Output Current Line
Regulation
Current Matching between
any two outputs
Efficiency
Conditions
Min
Typ Max Units
2.7
Active, No Load Current
EN=0
3113: 3.0 ≤ VIN ≤ 5.5 TA = 25°C, All
3114: 3.2 ≤ VIN ≤ 5.5 Outputs Max Current
3.0 ≤ VIN ≤ 5.5
18
1
5.5
2
1
V
mA
µA
20
22
mA
2
%/V
-2
VD1:Dn=3.6, VIN=3.3V
0.3
%
VIN=3.5, IOUT(total)=40mA
93
%
400
600
µs
KHz
Soft start time
Clock Frequency
Enable Threshold Low
VIN = 2.7 to 5.5V
Enable Threshold High
VIN = 2.7 to 5.5V
EN/SET low time
Minimum EN/SET high time
EN/SET Off Timeout
EN/SET input leakage
VIN = 5.5V
300
900
0.5
1.4
0.3
75
50
300
-1
500
1
V
V
µs
ns
µs
µA
3
AAT3113/4
High Efficiency 1.5X Fractional Charge
Pumps For White LED Applications
Typical Characteristics
(unless otherwise noted: VIN=3.5V, CIN=COUT=C1=C2=1µF, TA=25°C)
Quiescent Current vs. Temperature
Efficiency vs. Supply Voltage
100%
30 mA
1.000
95%
0.980
90%
Efficiency
0.960
IQ (mA)
20 mA
0.940
0.920
85%
40 mA
80%
75%
0.900
120 mA
70%
0.880
65%
0.860
60%
3.0
-40
-20
0
20
40
60
80
100
3.2
3.4
4.0
4.2
4.4
96%
1.2
94%
Efficiency (%)
1.1
1.0
IQ (mA)
3.8
Efficiency vs. Load Current
Quiescent Current vs. Supply Voltage
0.9
0.8
92%
90%
88%
86%
84%
82%
0.7
80%
0.6
3.0
3.5
4.0
4.5
5.0
0
5.5
20
40
60
80
100
120
Load Current (mA)
Supply Voltage (V)
Shutdown Current vs. Temperature
Oscillator Frequency vs. Temperature
1.000
710
700
690
680
0.100
FOSC (kHz)
Shutdown Current (µA)
3.6
Supply Voltage (V)
Temperature (°C)
0.010
670
660
650
640
630
0.001
-40
620
-20
0
20
40
Temperature (°C)
4
60 mA
80 mA
60
80
100
610
-40
-20
0
20
40
60
80
100
Temperature (°C)
3113.2004.07.1.4
AAT3113/4
High Efficiency 1.5X Fractional Charge
Pumps For White LED Applications
Typical Characteristics
(unless otherwise noted: VIN=3.5V, CIN=COUT=C1=C2=1µF, TA=25°C)
Normalized I DIODE vs. Temperature
IDIODE Response
-31dB to 0dB
1.020
1.010
ENSET
(2V/div)
IDIODE
1.000
0.990
0 dB
0.980
0.970
IDIODE
0.960
-31 dB
0.950
-40
-20
0
20
40
60
80
100
10 µs/div
Temperature (°C)
IDIODE vs. VIN
IDIODE Response
-9dB to -10dB
140
IDIODE (mA)
120
ENSET
(2V/div)
100
80
0 dB
60
-10 dB
40
IDIODE
20
-9 dB
0
3.0
3.5
4.0
-31 dB
4.5
10 µs/div
VIN (V)
VIH and VIL vs. VIN
140
1.000
120
0.975
0.950
VIH and VIL (V)
IDIODE (mA)
IDIODE vs. VDIODE
100
80
60
40
0.925
0.900
VIH
0.875
0.850
0.825
VIL
0.800
0.775
20
0
0.750
3.0
3.2
3.4
3.6
V DIODE (V)
3113.2004.07.1.4
3.8
4.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
VIN (V)
5
AAT3113/4
High Efficiency 1.5X Fractional Charge
Pumps For White LED Applications
Typical Characteristics
(unless otherwise noted: VIN=3.5V, CIN=COUT=C1=C2=1µF, TA=25°C)
Turn-On
Turn-Off
ENSET
(2V/div)
ENSET
(2V/div)
OUT
(5V/div)
OUT
(5V/div)
VDIODE
(5V/div)
VDIODE
(2V/div)
IIN
(50mA/div)
IIN
(50mA/div)
100µs/div
200µs/div
60mA Load Characteristics
40mA Load Characteristics
IN
OUT
20mV/div
10mV/div
OUT
IN
VDIODE
VDIODE
1µs/div
1µs/div
120mA Load Characteristics
80mA Load Characteristics
20mV/div
OUT
OUT
VDIODE
VDIODE
1µs/div
6
20mV/div
IN
IN
1µs/div
3113.2004.07.1.4
AAT3113/4
High Efficiency 1.5X Fractional Charge
Pumps For White LED Applications
Functional Block Diagram
VIN
Soft Start
C1+
C1-
1.5X
Charge
Pump
600kHz
Oscillator
C2+
C2-
Voltage
Reference
EN/SET
S2Cwire
Interface
5
32x8 bit
ROM
GND
Functional Description
The AAT3113/4 is a high efficiency 1.5X fractional
charge pump device intended for white LED back
light applications. The fractional charge pump consists of a linear regulator followed by a 1.5X charge
pump. The AAT3113/4 requires only four external
components: two 1µF ceramic capacitors for the
charge pump flying capacitors (C1 and C2), one
1µF ceramic capacitor for CIN, and one 0.33µF to
1µF ceramic capacitor for COUT. The charge pump
output is converted into four or six constant current
outputs (D1 to D4 or D6) to drive four or six individual LEDs with a maximum of 20mA each. The current source output magnitude is controlled by the
EN/SET serial data S2C interface. The interface
records rising edges of the EN/SET pin, and
3113.2004.07.1.4
OUT
8
Current
Mode
DAC
D1
D2
D3
D4
D5*
D6*
* AAT3114 only
decodes them into 32 individual current level settings each 1dB apart (see Current Level Settings
below). Code 32 is full scale, and Code 1 is full
scale attenuated by 31dB. The modulo 32 interface
wraps states back to state 1 after the 32nd clock.
With each EN/SET pulse, the output current increases by 1dB. To decrease the output current by 1dB,
31 EN/SET clock pulses are required. The counter
can be clocked at speeds up to 1Mhz, so intermediate states are not visible. The first rising edge of
EN/SET enables the IC and initially sets the output
LED current to -31dB, the lowest setting equal to
525µA. Once the final clock cycle is input for the
desired brightness level, the EN/SET pin is held high
to maintain the device output current at the programmed level. The device is disabled 500µs after
the EN/SET pin transitions to a logic low state.
7
AAT3113/4
High Efficiency 1.5X Fractional Charge
Pumps For White LED Applications
Applications Information
Current Level Settings
LED current level is set via the serial interface
according to a logarithmic scale where each code
is 1dB greater than the previous code. In this manner, the LED brightness appears linear with each
increasing code.
Normalized Current Level Settings
Normalized Current to Full Scale
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
Code
Current Levels (mA)
8
Code
20 mA max
Code
20 mA max
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
0.549
0.627
0.706
0.784
0.863
1.020
1.098
1.255
1.412
1.569
1.804
1.961
2.275
2.510
2.824
3.137
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
3.529
4.000
4.471
5.020
5.647
6.353
7.059
7.922
8.941
10.039
11.216
12.627
14.118
15.843
17.804
20.000
3113.2004.07.1.4
AAT3113/4
High Efficiency 1.5X Fractional Charge
Pumps For White LED Applications
EN/SET Serial Interface
EN/SET pin is held high to maintain the device output current at the programmed level. The device is
disabled 500µs after the EN/SET pin transitions to
a logic low state.
The current source output magnitude is controlled
by the EN/SET pin using AnalogicTech’s Simple
Serial Control (S2Cwire) interface. The interface
records rising edges of the EN/SET pin, and
decodes them into 32 individual current level settings each 1dB apart. Code 32 is full scale, and
Code 1 is full scale attenuated by 31dB. The modulo 32 interface wraps states back to state 1 after
the 32nd clock, so 1dB of attenuation is achieved
by clocking the EN/SET pin 31 times (see graph
titled “IDIODE Response -9dB to -10dB” on page
5). The counter can be clocked at speeds up to
1Mhz, so intermediate states are not visible. The
first rising edge of EN/SET enables the IC and initially sets the output LED current to -31dB, the lowest setting equal to 525µA. Once the final clock
cycle is input for the desired brightness level, the
The EN/SET timing is designed to accommodate a
wide range of data rates. After the first rising edge
of EN/SET, the charge pump is enabled and reaches full capacity after the soft start time (tSS). During
the soft start time, multiple clock pulses may be
entered on the EN/SET pin to set the final output
current level with a single burst of clocks.
Alternatively, the EN/SET clock pulses may be
entered one at a time to gradually increase the LED
brightness over any desired time period. A constant
current is sourced as long as EN/SET remains in a
logic high state. The current source outputs are
switched off after EN/SET has remained in a low
state for at least the tOFF timeout period.
EN/SET Timing
tLO
tHI
tOFF
EN/SET
Code
OFF
1
LED Selection
The AAT3113/4 devices are designed to drive white
LEDs with forward voltages of less than 4.2V.
Since the D1:D6 output current sources are
matched with negligible voltage dependence, the
LED brightness will be matched regardless of their
forward voltage matching.
Charge Pump Efficiency
The AAT3113/4 is a fractional charge pump. The
efficiency (η) can be simply defined as a linear voltage regulator with an effective output voltage that
is equal to one and a half times the input voltage.
Efficiency (η) for an ideal 1.5x charge pump can
typically be expressed as the output power divided
by the input power.
η = POUT / PIN
3113.2004.07.1.4
2
3
OFF
In addition, with an ideal 1.5x charge pump, the
output current may be expressed as 2/3 of the
input current. The expression to define the ideal
efficiency (η) can be rewritten as:
η=POUT/PIN=(VOUTxIOUT)/(VINx1.5IOUT)=VOUT/1.5VIN
η(%) = 100(VOUT / 1.5VIN)
For a charge pump with an output of 5 volts and a
nominal input of 3.5 volts, the theoretical efficiency is
95%. Due to internal switching losses and IC quiescent current consumption, the actual efficiency can
be measured at 93%. These figures are in close
agreement for output load conditions from 1mA to
100mA. Efficiency will decrease as load current
drops below 0.05mA or when level of VIN approaches VOUT. Refer to the Typical Characteristics section
for measured plots of efficiency versus input voltage
and output load current for the given charge pump
output voltage options.
9
AAT3113/4
High Efficiency 1.5X Fractional Charge
Pumps For White LED Applications
Power Efficiency and Device Evaluation:
Capacitor Characteristics
The charge pump efficiency discussion of the previous section only accounts for the efficiency of the
charge pump section itself. Due to the unique circuit
architecture and design of the AAT3113/14, it is very
difficult to measure efficiency in terms of a percent
value comparing input power over output power.
Since the AAT3113/14 outputs are pure constant current sources, it is difficult to measure the output voltage for a given output (D1 to D6) to derive an output
power measurement. For any given application,
white LED forward voltage levels can differ, yet the
output drive current will be maintained as a constant.
This makes quantifying output power a difficult task
when taken in the context of comparing to other
white LED driver circuit topologies. A better way to
quantify total device efficiency is to observe the total
input power to the device for a given LED current
drive level. The best White LED driver for a given
application should be based on trade-offs of size,
external component count, reliability, operating range
and total energy usage...Not just "% efficiency".
Ceramic composition capacitors are highly recommended over all other types of capacitors for use
with the AAT3113/4 products. Ceramic capacitors
offer many advantages over their tantalum and aluminum electrolytic counterparts. A ceramic capacitor typically has very low ESR, is lowest cost, has a
smaller PCB footprint and is non-polarized. Low
ESR ceramic capacitors help maximize charge
pump transient response. Since ceramic capacitors
are non-polarized, they are not prone to incorrect
connection damage.
Ceramic Capacitor Materials: Ceramic capacitors
less than 0.1µF are typically made from NPO or
COG materials. NPO and COG materials typically
have tight tolerance and are stable over temperature. Large capacitor values are typically composed of X7R, X5R, Z5U or Y5V dielectric materials. Large ceramic capacitors, typically greater
than 2.2µF are often available in low cost Y5V and
Z5U dielectrics, but large capacitors are not
required in the AAT3113/4 application.
AAT3114 Input Power vs. LED Current
700
VIN = 3.6V
Input Power (mW)
600
500
400
300
200
100
0
0
20
40
60
80
100
120
140
Output (LED) Current (mA)
Capacitor Selection
Careful selection of the four external capacitors
CIN, C1, C2, COUT is important because they will
affect turn on time, output ripple and transient performance. Optimum performance will be obtained
when low ESR (<100mΩ) ceramic capacitors are
used. In general, low ESR may be defined as less
than 100mΩ. A capacitor value of 1µF for all four
capacitors is a good starting point when choosing
capacitors. If the LED current sources are only
programmed for minimal current levels, then the
capacitor size may be decreased.
10
Equivalent Series Resistance (ESR): ESR is an
important characteristic to consider when selecting
a capacitor. ESR is a resistance internal to a
capacitor, which is caused by the leads, internal
connections, size or area, material composition
and ambient temperature. Capacitor ESR is typically measured in milliohms for ceramic capacitors
and can range to more than several ohms for tantalum or aluminum electrolytic capacitors.
Capacitor area is another contributor to ESR.
Capacitors that are physically large will have a lower
ESR when compared to an equivalent material
smaller capacitor. These larger devices can improve
circuit transient response when compared to an
equal value capacitor in a smaller package size.
Thermal Protection
The AAT3113/4 have a thermal protection circuit
that will shut down the charge pump and current
outputs if the die temperature rises above the thermal limit. However, thermal resistance of the QFN
package is so low, that if, in the case of the
AAT3114, all six outputs are shorted to ground at
maximum 20mA output level, the die temperature
will not rise sufficiently to trip the thermal protection.
The thermal protection will only trip if COUT is shorted to ground and the ambient temperature is high.
3113.2004.07.1.4
AAT3113/4
High Efficiency 1.5X Fractional Charge
Pumps For White LED Applications
Application Circuits
Typical AAT3113 Application Circuit:
VIN
C1+
C1
1µF
C1C2+
VOUT
CIN
1µF
VBATTERY
COUT
1µF
AAT3113
C2
1µF
C2-
EN/SET
EN/SET
D1
D2
D3
D4
GND
THI > 50ns
ON/1
2
3
D4
300ns < TLO < 75µs
4
5
6
D3
D2
D1
50ns minimum to enable
n
(n < =32)
OFF
Enable / Disable / LED Brightness Level Set Data Input
3113.2004.07.1.4
11
AAT3113/4
High Efficiency 1.5X Fractional Charge
Pumps For White LED Applications
Driving White LED display module back lights
and individual white LED's connected in parallel:
parallel connected. This feature is particularly useful to power pre-manufactured display modules
which are pre-wired with white LED backlights connected in a parallel circuit configuration. All output
may be connected in parallel to drive groups of
LED's as well. The internal current source reference circuit bases feedback from current sensed on
the D1 output. For best operation, the only requirement for this application is the output D1 should
always be connected to the load circuit.
The AAT3113/14 D1 to D6 outputs are true constant
current sources capable of driving up to 20mA each
over the operation input voltage range. Since these
outputs are true constant current sources, they may
be connected in parallel to drive a single power output. Any combination of outputs (D1 to D6) may be
connected in parallel. The maximum total output
current is a sum of how many current sources are
AAT3114 application driving a display module with six parallel connected white LEDs:
VIN
C1+
C1
1µF
C1C2+
VOUT
V BATTERY
CIN
1µF
COUT
1µF
AAT3114
C2
1µF
C2-
EN/SET
EN/SET
D1
D2
D3
D4
D5
D6
Display Module
D1
D2
D3
D4
D5
R
R
D6
GND
R
R
R
R
Resistor R is optional
AAT3114 Dual Backlight Control Circuit:
VIN
C1+
C1
1µF
C1C2+
VOUT
V BATTERY
CIN
1µF
COUT
1µF
AAT3114
C2
1µF
C2-
EN/SET
EN/SET
GND
Keyboard Backlight
D1
D2
D3
D4
D5
D6
Display Backlight
D4
D1
D2
D5
D6
D3
Enable Keyboard Backlight
Enable Display Backlight
12
3113.2004.07.1.4
AAT3113/4
High Efficiency 1.5X Fractional Charge
Pumps For White LED Applications
Ordering Information
Package
Marking1
Part Number (Tape and Reel)
QFN44-16
EUXYY
AAT3113ISN-20-T1
QFN44-16
FGXYY
AAT3114ISN-20-T1
TSOPJW-12
HTXYY
AAT3113ITP-20-T1
Note: Sample stock is generally held on all part numbers listed in BOLD.
Note 1: XYY = assembly and date code.
Package Information
0.330 ± 0.050
Pin 1 Identification
13
16
0.650 BSC
1
R0.030Max
4
9
8
4.000 ± 0.050
2.400 ± 0.050
5
2.280 REF
Top View
0.0125 ± 0.0125
Bottom View
0.203 ± 0.025
0.900 ± 0.050
4.000 ± 0.050
Pin 1 Dot By Marking
0.450 ± 0.050
0.600 ± 0.050
QFN44-16
Side View
All dimensions in millimeters.
3113.2004.07.1.4
13
AAT3113/4
High Efficiency 1.5X Fractional Charge
Pumps For White LED Applications
TSOPJW-12
2.85 ± 0.20
2.40 ± 0.10
0.10
0.20 +- 0.05
0.50 BSC 0.50 BSC 0.50 BSC 0.50 BSC 0.50 BSC
7° NOM
0.055 ± 0.045
0.04 REF
0.15 ± 0.05
+ 0.10
1.00 - 0.065
0.9625 ± 0.0375
3.00 ± 0.10
4° ± 4°
0.45 ± 0.15
0.010
2.75 ± 0.25
All dimensions in millimeters.
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rights, or other intellectual property rights are implied.
AnalogicTech reserves the right to make changes to their products or specifications or to discontinue any product or service without notice, and advise customers to obtain the latest
version of relevant information to verify, before placing orders, that information being relied on is current and complete. All products are sold subject to the terms and conditions of sale
supplied at the time of order acknowledgement, including those pertaining to warranty, patent infringement, and limitation of liability.
AnalogicTech warrants performance of its semiconductor products to the specifications applicable at the time of sale in accordance with AnalogicTech’s standard warranty. Testing and
other quality control techniques are utilized to the extent AnalogicTech deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily
performed.
Advanced Analogic Technologies, Inc.
830 E. Arques Avenue, Sunnyvale, CA 94085
Phone (408) 737-4600
Fax (408) 737-4611
14
3113.2004.07.1.4
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