AD AD8213

Dual, High Voltage
Current Shunt Monitor
AD8213
±4000 V HBM ESD
High common-mode voltage range
−2 V to +65 V operating
−3 V to +68 V survival
Buffered output voltage
Wide operating temperature range
10-lead MSOP: −40°C to +125°C
Excellent ac and dc performance
3 μV/°C typical offset drift
−10 ppm/°C typical gain drift
120 dB typical CMRR at dc
APPLICATIONS
FUNCTIONAL BLOCK DIAGRAM
–IN2
+IN2 +IN1
A2
–IN1
A1
PROPRIETARY
OFFSET
CIRCUITRY
V+
PROPRIETARY
OFFSET
CIRCUITRY
OUT2
OUT1
G = +20
G = +20
AD8213
CF2
GND
CF1
06639-001
FEATURES
Figure 1.
High-side current sensing
Motor controls
Transmission controls
Diesel injection controls
Engine management
Suspension controls
Vehicle dynamic controls
DC-to-DC converters
GENERAL DESCRIPTION
The AD8213 is a dual-channel, precision current sense amplifier. It
features a set gain of 20 V/V, with a maximum ±0.5% gain error
over the entire temperature range. The buffered output voltage
directly interfaces with any typical converter. Excellent commonmode rejection from −2 V to +65 V, is independent of the 5 V
supply. The AD8213 performs unidirectional current measurements across a shunt resistor in a variety of industrial and
automotive applications, such as motor control, solenoid
control, or battery management.
Special circuitry is devoted to output linearity being maintained
throughout the input differential voltage range of 0 mV to 250 mV,
regardless of the common-mode voltage present. The AD8213
also features additional pins that allow the user to low-pass filter
the input signal before amplifying, via an external capacitor to
ground. The AD8213 has an operating temperature range of
−40ºC to +125ºC and is offered in a small 10-lead MSOP package.
Rev. 0
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other
rights of third parties that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarks and registered trademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
www.analog.com
Fax: 781.461.3113
©2007 Analog Devices, Inc. All rights reserved.
AD8213
TABLE OF CONTENTS
Features .............................................................................................. 1
Application Notes ........................................................................... 11
Applications....................................................................................... 1
Output Linearity......................................................................... 11
Functional Block Diagram .............................................................. 1
Low-Pass Filtering...................................................................... 11
General Description ......................................................................... 1
Applications Information .............................................................. 12
Revision History ............................................................................... 2
High-Side Current Sense with a Low-Side Switch................. 12
Specifications..................................................................................... 3
High-Side Current Sensing ....................................................... 12
Absolute Maximum Ratings............................................................ 4
Low-Side Current Sensing ........................................................ 12
ESD Caution.................................................................................. 4
Bidirectional Current Sensing .................................................. 13
Pin Configuration and Function Descriptions............................. 5
Outline Dimensions ....................................................................... 14
Typical Performance Characteristics ............................................. 6
Ordering Guide .......................................................................... 14
Theory of Operation ...................................................................... 10
REVISION HISTORY
5/07—Revision 0: Initial Version
Rev. 0 | Page 2 of 16
AD8213
SPECIFICATIONS
TOPR = operating temperature range, VS = 5 V, RL = 25 kΩ (RL is the output load resistor), unless otherwise noted.
Table 1.
Parameter
GAIN
Initial
Accuracy
Accuracy Over Temperature
Gain vs. Temperature
VOLTAGE OFFSET
Offset Voltage (RTI)
Over Temperature (RTI)
Offset Drift
INPUT
Input Impedance
Differential
Common Mode
Common-Mode Input Voltage Range
Differential Input Voltage Range
Common-Mode Rejection
OUTPUT
Output Voltage Range Low
Output Voltage Range High
Output Impedance
FILTER RESISTOR
DYNAMIC RESPONSE
Small Signal −3 dB Bandwidth
Slew Rate
NOISE
0.1 Hz to 10 Hz, RTI
Spectral Density, 1 kHz, RTI
POWER SUPPLY
Operating Range
Quiescent Current Over Temperature
Power Supply Rejection Ratio
TEMPERATURE RANGE
For Specified Performance
1
Min
AD8213
Typ
Max
Unit
Conditions
±0.5
−25
V/V
%
%
ppm/°C
VO ≥ 0.1 V dc
TOPR
±1
±2.2
±12
mV
mV
μV/°C
25°C
TOPR
TOPR
+65
250
120
90
kΩ
MΩ
kΩ
V
mV
dB
dB
V common mode > 5 V
V common mode < 5 V
Common mode continuous
Differential input voltage
TOPR, f = DC, VCM > 5 V (see Figure 5)
TOPR, f = DC, VCM < 5 V (see Figure 5)
0.05
4.95
2
20
V
V
Ω
kΩ
CF access to resistor for low-pass filter
500
4.5
2.7
kHz
V/μs
V/μs
COUT = 20 pF, no filter capacitor (CF)
COUT = 20 pF, CF = 20 pF
7
70
μV p-p
nV/√Hz
20
±0.25
0
−10
5
5
3.5
−2
100
80
0.1
18
4.5
2.5
4.9
22
5.5
3.75
76
−40
V
mA
VCM > 5 V, per amplifier 1 , total supply
current for two channels
dB
+125
°C
When the input common mode is less than 5 V, the supply current increases. This can be calculated by IS = −0.52(VCM) + 4.9 (see Figure 11).
Rev. 0 | Page 3 of 16
AD8213
ABSOLUTE MAXIMUM RATINGS
Table 2.
Parameter
Supply Voltage
Continuous Input Voltage
Reverse Supply Voltage
HBM (Human Body Model) ESD Rating
CDM (Charged Device Model) ESD Rating
Operating Temperature Range
Storage Temperature Range
Output Short-Circuit Duration
Rating
12.5 V
−3 V to +68 V
−0.3 V
±4000 V
±1000 V
−40°C to +125°C
−65°C to +150°C
Indefinite
Stresses above those listed under Absolute Maximum Ratings
may cause permanent damage to the device. This is a stress
rating only; functional operation of the device at these or any
other conditions above those indicated in the operational
section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect
device reliability.
ESD CAUTION
Rev. 0 | Page 4 of 16
AD8213
1
10
2
9
–IN2 1
10
–IN1
AD8213
9
+IN1
TOP VIEW
(Not to Scale)
8
V+
7
OUT1
6
CF1
+IN2 2
3
8
GND 3
OUT2 4
CF2 5
Figure 3. Pin Configuration
7
6
5
06639-002
4
Figure 2. Metallization Diagram
Table 3. Pin Function Descriptions
Pin No.
1
2
3
4
5
6
7
8
9
10
Mnemonic
−IN2
+IN2
GND
OUT2
CF2
CF1
OUT1
V+
+IN1
−IN1
X
−401
−401
−401
−394
−448
448
394
401
401
401
Y
677
510
−53
−500
−768
−768
−500
−61
510
677
Description
Inverting input of the second channel.
Noninverting input of the second channel.
Ground.
Output of the second channel.
Low-pass filter pin for the second channel.
Low-pass filter pin for the first channel.
Output of the first channel.
Supply.
Noninverting input of the first channel.
Inverting input of the first channel.
Rev. 0 | Page 5 of 16
06639-003
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
AD8213
TYPICAL PERFORMANCE CHARACTERISTICS
0.8
0.7
40
35
30
25
20
0
–0.1
–0.2
–0.3
–0.4
–0.5
–0.6
–0.7
–20
0
20
40
60
80
100
120
TEMPERATURE (°C)
–40
10k
06639-104
–0.8
–40
10M
Figure 7. Typical Small Signal Bandwidth
(VOUT = 200 mV p-p)
10
COMMON-MODE VOLTAGE > 5V
110
100
90 COMMON-MODE VOLTAGE < 5V
80
70
60
100
1k
10k
100k
1M
FREQUENCY (Hz)
8
7
6
5
4
3
2
1
0
–1
06639-005
50
10
9
DIFFERENTIAL INPUT VOLTAGE (mV)
Figure 5. CMRR vs. Frequency
Figure 8. Total Output Error vs. Differential Input Voltage
2500
–475
2000
–480
–485
INPUT BIAS CURRENT (nA)
1500
1000
500
0
–500
–1000
–1500
–490
–495
–500
+IN
–505
–510
–515
–520
–525
–2000
–IN
–530
–20
0
20
40
60
TEMPERATURE (°C)
80
100
120
06639-102
–2500
–40
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 250
–535
0
25
50
75
100
125
150
175
200
225
DIFFERENTIAL INPUT VOLTAGE (mV)
Figure 9. Input Bias Current vs. Differential Input Voltage
(VCM = 0 V) (Per Channel)
Figure 6. Typical Gain Drift
Rev. 0 | Page 6 of 16
250
06639-010
120
06639-013
OUTPUT ERROR (%)
(% ERROR OF THE IDEAL OUTPUT VALUE)
130
CMRR (dB)
1M
FREQUENCY (Hz)
Figure 4. Typical Offset Drift
GAIN ERROR (ppm)
100k
06639-008
15
10
5
0
–5
–10
–15
–20
–25
–30
–35
GAIN (dB)
VOSI (mV)
0.6
0.5
0.4
0.3
0.2
0.1
AD8213
0.2
INPUT
100mV/DIV
–0.2
OUTPUT
–0.4
–0.6
OUTPUT
1V/DIV, CF = 20pF
–0.8
1V/DIV, CF = 100pF
–1.2
–5
5
15
25
35
45
55
65
INPUT COMMON-MODE VOLTAGE (V)
06639-011
–1.0
06639-015
INPUT BIAS CURRENT (mA)
0
TIME (2µs/DIV)
Figure 10. Input Bias Current vs. Common-Mode Voltage
(Per Input)
Figure 13. Rise Time
7.0
6.5
200mV/DIV
5.5
5.0
INPUT
4.5
4.0
3.5
2V/DIV, CF = 20pF
3.0
2.5
2.0
OUTPUT
–2
0
2
4
6
8
65
COMMON-MODE VOLTAGE (V)
06639-016
1.0
–4
06639-012
1.5
TIME (1µs/DIV)
Figure 11. Supply Current vs. Common-Mode Voltage
Figure 14. Differential Overload Recovery (Falling)
100mV/DIV
INPUT
INPUT
200mV/DIV
1V/DIV, CF = 20pF
OUTPUT
OUTPUT
OUTPUT
TIME (2µs/DIV)
2V/DIV, CF = 20pF
TIME (1µs/DIV)
Figure 12. Fall Time
Figure 15. Differential Overload Recovery (Rising)
Rev. 0 | Page 7 of 16
06639-017
1V/DIV, CF = 100pF
06639-014
SUPPLY CURRENT (mA)
6.0
AD8213
0.01/DIV
10
9
8
7
6
5
4
3
2
1
0
–40
06639-105
TIME (5µs/DIV)
11
–20
0
20
40
60
80
100
120
140
TEMPERATURE (°C)
Figure 16. Settling Time (Falling)
06639-021
MAXIMUM OUTPUT SOURCE CURRENT (mA)
12
2V/DIV
Figure 19. Output Source Current vs. Temperature
(Per Channel)
5.0
4.9
OUTPUT VOLTAGE RANGE (V)
4.8
2V/DIV
0.01/DIV
4.7
4.6
4.5
4.4
4.3
4.2
4.1
4.0
3.9
3.8
3.7
06639-106
3.5
TIME (5µs/DIV)
Figure 20. Output Voltage Range vs. Output Source Current
(Per Channel)
12
2.0
10
9
8
7
6
5
4
3
2
1
–20
0
20
40
60
80
100
120
TEMPERATURE (°C)
140
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
0
1
2
3
4
5
6
7
OUTPUT SINK CURRENT (mA)
Figure 18. Output Sink Current vs. Temperature
(Per Channel)
8
9
10
06639-024
OUTPUT VOLTAGE RANGE FROM GND (V)
11
06639-020
MAXIMUM OUTPUT SINK CURRENT (mA)
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5
OUTPUT SOURCE CURRENT (mA)
Figure 17. Settling Time (Rising)
0
–40
0
06639-023
3.6
Figure 21. Output Voltage Range from GND vs. Output Sink Current
(Per Channel)
Rev. 0 | Page 8 of 16
AD8213
2100
TEMP = –40°C
TEMP = +25°C
TEMP = +125°C
1000
1800
1500
600
COUNT
COUNT
800
400
1200
900
600
200
–10
–5
0
5
10
15
VOS (µV/°C)
0
–2.0
06639-006
0
–15
1200
800
600
400
200
–18
–15
–12
–9
–6
GAIN DRIFT (ppm/°C)
–3
0
06639-101
COUNT
1000
–21
–0.5
0
0.5
1.0
Figure 24. Offset Distribution (mV)
(VCM = 6 V)
1400
–24
–1.0
VOS (mV)
Figure 22. Offset Drift Distribution (μV/°C)
(Temperature Range = −40°C to +125°C)
0
–1.5
Figure 23. Gain Drift Distribution (ppm/°C)
(Temperature Range = −40°C to +125°C)
Rev. 0 | Page 9 of 16
1.5
2.0
06639-103
300
AD8213
THEORY OF OPERATION
In typical applications, the AD8213 amplifies a small differential
input voltage generated by the load current flowing through a
shunt resistor. The AD8213 rejects high common-mode
voltages (up to 65 V) and provides a ground referenced, buffered
output that interfaces with an analog-to-digital converter (ADC).
Figure 25 shows a simplified schematic of the AD8213.
This current (IIN1) is converted back to a voltage via ROUT1. The
output buffer amplifier has a gain of 20 V/V, and offers excellent
accuracy as the internal gain setting resistors are precision
trimmed to within 0.01% matching. The resulting output
voltage is equal to
The following explanation refers exclusively to Channel 1 of the
AD8213, however, the same explanation applies to Channel 2.
Prior to the buffer amplifier, a precision-trimmed 20 kΩ resistor
is available to perform low-pass filtering of the input signal
prior to the amplification stage. This means that the noise of the
input signal is not amplified, but rejected, resulting in a more
precise output signal that will directly interface with a converter.
A capacitor from the CF1 pin to GND, will result in a low-pass
filter with a corner frequency of
VOUT1 = (ISHUNT1 × RSHUNT1) × 20
A load current flowing through the external shunt resistor
produces a voltage at the input terminals of the AD8213. The
input terminals are connected to Amplifier A1 by Resistor R1(1)
and Resistor R1(2). The inverting terminal, which has very high
input impedance is held to (VCM) – (ISHUNT × RSHUNT), since
negligible current flows through Resistor R1(2). Amplifier A1
forces the noninverting input to the same potential. Therefore,
the current that flows through Resistor R1(1), is equal to
f −3dB =
1
2 π(20000 )C FILTER
IIN1 = (ISHUNT1 × RSHUNT1)/R1(1)
ISHUNT2
ISHUNT1
RSHUNT2
RSHUNT1
IIN1
R2 (2)
R2 (1)
R1 (1)
A2
A1
PROPRIETARY
OFFSET
CIRCUITRY
20kΩ
ROUT2
G = +20
V+
PROPRIETARY
OFFSET
CIRCUITRY
Q1
Q2
20kΩ
OUT2 = (ISHUNT2 × RSHUNT2 ) × 20
R1 (2)
OUT1 = (ISHUNT1 × RSHUNT1 ) × 20
ROUT1
G = +20
AD8213
CF2
GND
CF1
Figure 25. Simplified Schematic
Rev. 0 | Page 10 of 16
06639-028
IIN2
AD8213
APPLICATION NOTES
OUTPUT LINEARITY
LOW-PASS FILTERING
In all current sensing applications, and especially in automotive
and industrial environments where the common-mode voltage
can vary significantly, it is important that the current sensor
maintain the specified output linearity, regardless of the input
differential or common-mode voltage. The AD8213 contains
specific circuitry on the input stage, which ensures that even
when the differential input voltage is very small, and the
common-mode voltage is also low (below the 5 V supply), the
input to output linearity is maintained. Figure 26 displays the
input differential voltage versus the corresponding output
voltage at different common modes.
In typical applications, such as motor and solenoid current
sensing, filtering the differential input signal of the AD8213
could be beneficial in reducing differential common-mode
noise as well as transients and current ripples flowing through
the input shunt resistor. Typically, such a filter can be implemented by adding a resistor in series with each input and a
capacitor directly between the input pins. However, the AD8213
features a filter pin available after the input stage, but before the
final amplification stage. The user can connect a capacitor to
ground, making a low-pass filter with the internal precisiontrimmed 20 kΩ resistor. This means the no gain or CMRR
errors are introduced by adding resistors at the input of the
AD8213. Figure 27 shows the typical connection.
220
200
180
160
ISHUNT1
RSHUNT2
RSHUNT1
R2 (1)
120
R2 (2)
R1 (1)
R1 (2)
VOUT @ VCM = 65V
100
A2
VOUT @ VCM = 0V
80
A1
PROPRIETARY
OFFSET
CIRCUITRY
60
40
20kΩ
20
V+
PROPRIETARY
OFFSET
CIRCUITRY
20kΩ
IDEAL VOUT
0
1
2
3
4
5
6
7
VIN DIFFERENTIAL (mV)
8
9
10
G = +20
06639-029
0
AD8213
Figure 26. Gain Linearity Due to Differential and Common-Mode Voltage
The AD8213 provides a correct output voltage, regardless of the
common mode, when the input differential is at least 2 mV.
This is due to the voltage range of the output amplifier that can
go as low as 33 mV typical. The specified minimum output
amplifier voltage is 100 mV in order to provide sufficient
guardbands. The ability of the AD8213 to work with very small
differential inputs regardless of the common-mode voltage,
allows for more dynamic range, accuracy, and flexibility in any
current sensing application.
G = +20
CF2
GND
CAP2
CF1
CAP1
06639-030
VOUT (mV)
140
ISHUNT2
Figure 27. Filter Capacitor Connections
The 3 dB frequency of this low-pass filter is calculated using the
following formula:
f −3dB =
1
2 π(20000 )C FILTER
It is recommended that in order to prevent output chatter due
to noise potentially entering through the filter pin and coupling
to the output, a capacitor is always placed from the filter pin to
GND. This can be a ≈20 pF capacitor in cases when all of the
bandwidth of the AD8213 is needed in the application.
Rev. 0 | Page 11 of 16
AD8213
APPLICATIONS INFORMATION
OVERCURRENT
DETECTION (<100ns)
HIGH-SIDE CURRENT SENSE WITH A LOW-SIDE
SWITCH
8
SHUNT
+IN2
+IN1
9
3
GND
4
OUT2
5
CF2
CAP2
V+
8
OUT1
7
CF1
6
4
5
6
7
8
OUT GND NC
–IN
AD8214
NC VREG +IN
SHUNT
3
2
VS
1
SHUNT
AD8213
LOAD
1
–IN2
–IN1 10
2
+IN2
+IN1
9
3
GND
V+
8
4
OUT2
OUT1
7
5
CF2
CF1
6
5V
LOAD
BATTERY
4
CAP2
SWITCH
CAP1
CLAMP
DIODE
5V
CAP1
SHUNT
BATTERY
Figure 29. Battery Referenced Shunt Resistor
LOW-SIDE CURRENT SENSING
SWITCH
06639-031
SWITCH
–IN1 10
2
3
06639-032
BATTERY
AD8213
–IN2
2
OVERCURRENT
DETECTION (<100ns)
INDUCTIVE
LOAD
1
+IN VREG NC
Figure 28. Low-Side Switch
HIGH-SIDE CURRENT SENSING
In this configuration, the shunt resistor is referenced to the
battery. High voltage will be present at the inputs of the current
sense amplifier. In this mode, the recirculation current is again
measured and shorts to ground can be detected. When the
shunt is battery referenced the AD8213 produces a linear
ground referenced analog output. An AD8214 can also be used
to provide an overcurrent detection signal in as little as 100 ns.
This feature will be useful in high current systems, where fast
shutdown in overcurrent conditions is essential.
In systems where low-side current sensing is preferred, the
AD8213 provides an integrated solution with great accuracy.
Ground noise is rejected, CMRR is typical higher than 90 dB, and
output linearity is not compromised, regardless of the input
differential voltage.
INDUCTIVE
LOAD
BATTERY
Rev. 0 | Page 12 of 16
INDUCTIVE
LOAD
AD8213
CLAMP
DIODE
1
–IN2
–IN1 10
CLAMP
DIODE
SWITCH
2
+IN2
+IN1
9
SWITCH
3
GND
4
OUT2
5
CF2
SHUNT
V+
8
OUT1
7
CF1
6
5V
BATTERY
SHUNT
06639-033
CLAMP
DIODE
5
VS
1
SWITCH
INDUCTIVE
LOAD
6
NC GND OUT
AD8214
BATTERY
In such load control configurations, the PWM controlled switch
is ground referenced. An inductive load (solenoid) is tied to a
power supply. A resistive shunt is placed between the switch and
the load (see Figure 28). An advantage of placing the shunt on
the high side is that the entire current, including the recirculation current, can be measured, because the shunt remains in
the loop when the switch is off. In addition, diagnostics can be
enhanced because shorts to ground can be detected with the
shunt on the high side. In this circuit configuration, when the
switch is closed, the common-mode voltage moves down to
near the negative rail. When the switch is opened, the voltage
reversal across the inductive load causes the common-mode
voltage to be held one diode drop above the battery by the
clamp diode.
7
–IN
Figure 30. Ground Referenced Shunt Resistor
AD8213
ICHARGE
BIDIRECTIONAL CURRENT SENSING
The AD8213 can also be configured to sense current in both
directions at the inputs. This configuration is useful in charge/
discharge applications. A typical connection diagram is shown
in Figure 31. In this mode Channel 1 monitors ILOAD and
Channel 2 monitors ICHARGE.
ILOAD
RSHUNT
BATTERY
+IN
LOAD
CHARGER
–IN
V+
ICHARGE
ILOAD
BATTERY
AD8210
0.1µF
RSHUNT
LOAD
VREF 1
CHARGER
G = +20
AD8213
–IN2
–IN1 10
2
+IN2
+IN1
9
3
GND
V+
8
4
OUT2
OUT1
7
5
CF2
VREF 2
GND
6
CF1
06639-034
CF2
CF1
5V
06639-035
1
OUTPUT
Figure 32. AD8210 in Bidirectional Applications
Figure 31. Bidirectional Current Sensing
For applications requiring a bidirectional current measurement,
an optimal solution could be to use a single channel device,
which offers the same functionality as the previous circuit. The
AD8210 is a single channel current sensor featuring bidirectional capability. The typical connection diagram for the
AD8210 in bidirectional applications is shown in Figure 32.
Rev. 0 | Page 13 of 16
AD8213
OUTLINE DIMENSIONS
3.10
3.00
2.90
10
3.10
3.00
2.90
1
6
5
5.15
4.90
4.65
PIN 1
0.50 BSC
0.95
0.85
0.75
1.10 MAX
0.15
0.05
0.33
0.17
SEATING
PLANE
0.23
0.08
8°
0°
0.80
0.60
0.40
COPLANARITY
0.10
COMPLIANT TO JEDEC STANDARDS MO-187-BA
Figure 33. 10-Lead Mini Small Outline Package [MSOP]
(RM-10)
Dimensions shown in millimeters
ORDERING GUIDE
Model
AD8213YRMZ 1
AD8213YRMZ-RL1
AD8213YRMZ-RL71
1
Temperature Range
−40°C to +125°C
−40°C to +125°C
−40°C to +125°C
Package Description
10-Lead MSOP
10-Lead MSOP, 13” Tape and Reel
10-Lead MSOP, 7” Tape and Reel
Z = RoHS Compliant Part.
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Package Option
RM-10
RM-10
RM-10
Branding
HOU
HOU
HOU
AD8213
NOTES
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AD8213
NOTES
©2007 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D06639-0-5/07(0)
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