High Voltage Current Shunt Monitor AD8211

High Voltage
Current Shunt Monitor
AD8211
±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
5-lead SOT: −40°C to +125°C
Excellent ac and dc performance
5 μV/°C typical offset drift
−13 ppm/°C typical gain drift
120 dB typical CMRR at dc
FUNCTIONAL BLOCK DIAGRAM
VIN+
VIN–
V+
A1
PROPRIETARY
OFFSET
CIRCUITRY
OUT
G = +20
AD8211
APPLICATIONS
High-side current sensing
Motor controls
Transmission controls
Engine management
Suspension controls
Vehicle dynamic controls
DC-to-dc converters
GND
06824-001
FEATURES
Figure 1.
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GENERAL DESCRIPTION
The AD8211 is a high voltage, precision current shunt amplifier.
It features a set gain of 20 V/V, with a typical ±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 AD8211 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 AD8211
has an operating temperature range of −40°C to +125°C and is
offered in a small 5-lead SOT package.
Rev. 0
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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
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Fax: 781.461.3113
©2007 Analog Devices, Inc. All rights reserved.
AD8211
TABLE OF CONTENTS
Features .............................................................................................. 1
Theory of Operation ...................................................................... 10
Applications....................................................................................... 1
Application Notes ........................................................................... 11
Functional Block Diagram .............................................................. 1
Output Linearity......................................................................... 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
Outline Dimensions ....................................................................... 13
Pin Configuration and Function Descriptions............................. 5
Ordering Guide .......................................................................... 13
Typical Performance Characteristics ............................................. 6
REVISION HISTORY
7/07—Revision 0: Initial Version
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Rev. 0 | Page 2 of 16
AD8211
SPECIFICATIONS
TOPR = −40°C to +125°C, TA = 25°C, 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
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
Min
Typ
Max
20
±0.25
±0.35
−13
±1
±2.2
5
5
5
3.5
−2
100
80
+65
250
120
90
Unit
Conditions
V/V
%
%
ppm/°C
VO ≥ 0.1 V dc
TOPR
TOPR 1
mV
mV
μV/°C
25°C
TOPR
TOPR 2
kΩ
MΩ
kΩ
V
mV
dB
dB
Common-mode voltage > 5 V
Common-mode voltage < 5 V
Common-mode continuous
Differential input voltage
TA, f = dc, VCM > 5 V, see Figure 5
TA, f = dc, VCM < 5 V, see Figure 5
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0.1
0.05
4.95
2
4.9
500
4.5
kHz
V/μs
7
70
μV p-p
nV/√Hz
4.5
1.2
5.5
2.0
V
mA
dB
+125
°C
76
−40
V
V
Ω
1
VCM > 5 V 3 , see Figure 12
The mean of the gain drift distribution is typically −13 ppm/°C, with a σ = 3 ppm/°C.
The mean of the offset drift distribution is typically +5 μV/°C, with a σ = 3 μV/°C.
3
When the input common-mode voltage is less than 5 V, the supply current increases, which can be calculated by IS = −0.275 (VCM) + 2.5.
2
Rev. 0 | Page 3 of 16
AD8211
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
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Rev. 0 | Page 4 of 16
AD8211
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
OUT 1
5
V+
4
VIN–
AD8211
2
GND 2
5
VIN+ 3
TOP VIEW
(Not to Scale)
NC = NO CONNECT
06824-002
1
3
4
06824-030
Figure 3. Pin Configuration
Figure 2. Metallization Diagram
Table 3. Pin Function Descriptions
Pin No.
1
2
3
4
5
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Mnemonic
OUT
GND
VIN+
VIN−
V+
X
−277
−140
−228
+229
+264
Y
+466
+466
−519
−519
+466
Description
Buffered Output.
Ground.
Noninverting Input.
Inverting Input.
Supply.
Rev. 0 | Page 5 of 16
AD8211
TYPICAL PERFORMANCE CHARACTERISTICS
1.2
40
35
1.0
30
0.8
25
20
15
GAIN (dB)
0.2
0
–0.2
10
5
0
–5
–0.4
–10
–15
–0.6
–20
–0.8
–25
–30
06824-112
VOSI (mV)
0.4
–1.0
–1.2
–40
–20
0
20
40
60
80
100
06824-107
0.6
–35
–40
10k
120
100k
TEMPERATURE (°C)
10M
Figure 7. Typical Small Signal Bandwidth (VOUT = 200 mV p-p)
Figure 4. Typical Offset vs. Temperature
140
10
9
130
TOTAL OUTPUT ERROR (%)
COMMON-MODE VOLTAGE > 5V
120
CMRR (dB)
1M
FREQUENCY (Hz)
110
100
80
7
6
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COMMON-MODE VOLTAGE < 5V
90
8
5
4
3
06824-114
60
10
100
1k
10k
100k
06824-118
2
70
1
0
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 250
1M
FREQUNCY (Hz)
DIFFERENTIAL INPUT VOLTAGE (mV)
Figure 5. Typical CMRR vs. Frequency
Figure 8. Total Output Error vs. Differential Input Voltage
2500
–510
2000
–515
–520
500
0
–500
–1000
–1500
–530
–535
VIN+
–540
–545
–550
–555
–560
–2000
–2500
–40
–525
–20
0
20
40
60
80
100
VIN–
06824-103
INPUT BIAS CURRENT (µA)
1000
06824-113
GAIN ERROR (PPM)
1500
–565
–570
0
120
TEMPERATURE (°C)
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
Figure 6. Typical Gain Error vs. Temperature
Rev. 0 | Page 6 of 16
250
AD8211
110
100mV/DIV
90
INPUT
VIN+
80
1V/DIV
70
VIN–
60
OUTPUT
06824-104
50
40
0
25
50
75
100
125
150
175
200
225
06824-110
INPUT BIAS CURRENT (µA)
100
250
TIME (500ns/DIV)
DIFFERENTIAL INPUT VOLTAGE (mV)
Figure 10. Input Bias Current vs. Differential Input Voltage,
VCM = 5 V
Figure 13. Fall Time
0.8
INPUT
0
100mV/DIV
–0.4
OUTPUT
–0.8
–1.6
–2.0
1V/DIV
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–2.4
–5
0
5
10
15
20
25
30
35
40
45
50
55
60
65
06824-111
–1.2
06824-102
INPUT BIAS CURRENT (mA)
0.4
TIME (500ns/DIV)
INPUT COMMON-MODE VOLTAGE (V)
Figure 11. Input Bias Current vs. Input Common-Mode Voltage
Figure 14. Rise Time
4.0
200mV/DIV
3.0
INPUT
2.5
2V/DIV
2.0
1.5
OUTPUT
–2
0
2
4
6
8
06824-109
1.0
–4
06824-101
SUPPLY CURRENT (mA)
3.5
65
TIME (1µs/DIV)
COMMON-MODE VOLTAGE (V)
Figure 12. Supply Current vs. Common-Mode Voltage
Figure 15. Differential Overload Recovery (Falling)
Rev. 0 | Page 7 of 16
AD8211
INPUT
200mV/DIV
OUTPUT
06824-108
2V/DIV
11.5
11.0
10.5
10.0
9.5
9.0
8.5
8.0
7.5
7.0
6.5
6.0
06824-106
MAXIMUM OUTPUT SINK CURRENT (mA)
12.0
5.5
5.0
–40 –30 –20 –10 0
10 20 30 40 50 60 70 80 90 100 110 120 130 140 150
TIME (1µs/DIV)
TEMPERATURE (°C)
Figure 19. Maximum Output Sink Current vs. Temperature
Figure 16. Differential Overload Recovery (Rising)
MAXIMUM OUTPUT SOURCE CURRENT (mA)
9.0
2V/DIV
8.0
7.5
7.0
6.5
6.0
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5.5
5.0
4.5
4.0
–40
TIME 5µs/DIV)
06824-105
06824-120
0.01/DIV
8.5
–20
0
20
40
60
80
100
120
140
TEMPERATURE (°C)
Figure 20. Maximum Output Source Current vs. Temperature
Figure 17. Settling Time (Falling)
5.0
2V/DIV
06824-119
0.01/DIV
4.2
3.8
3.4
3.0
2.6
2.2
1.8
06824-117
OUTPUT VOLTAGE RANGE (V)
4.6
1.4
1.0
TIME 5µs/DIV)
0
1
2
3
4
5
6
7
8
OUTPUT SOURCE CURRENT (mA)
Figure 21. Output Voltage Range vs. Output Source Current
Figure 18. Settling Time (Rising)
Rev. 0 | Page 8 of 16
9
AD8211
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
06824-116
OUTPUT VOLTAGE RANGE FROM GND (V)
2.0
0.2
0
0
1
2
3
4
5
6
7
8
9
10
11
12
OUTPUT SINK CURRENT (mA)
Figure 22. Output Voltage Range from GND vs. Output Sink Current
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Rev. 0 | Page 9 of 16
AD8211
THEORY OF OPERATION
In typical applications, the AD8211 amplifies a small differential
input voltage generated by the load current flowing through
a shunt resistor. The AD8211 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 23 shows a simplified schematic of the AD8211.
ISHUNT
(VCM) − (ISHUNT × RSHUNT)
because negligible current flows through Resistor R. Amplifier
A1 forces the noninverting input to the same potential. Therefore,
the current that flows through Resistor R1, is equal to
RSHUNT
IIN
A load current flowing through the external shunt resistor
produces a voltage at the input terminals of the AD8211. The
input terminals are connected to Amplifier A1 by Resistor R
and Resistor R1. The inverting terminal, which has very high
input impedance is held to
R
R1
IIN = (ISHUNT × RSHUNT)/R1
V+
A1
PROPRIETARY
OFFSET
CIRCUITRY
This current (IIN) is converted back to a voltage via ROUT. 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
Q1
VOUT = (ISHUNT × RSHUNT) × 20
VOUT = (ISHUNT × RSHUNT ) × 20
AD8211
GND
06824-022
G = +20
ROUT
Figure 23. Simplified Schematic
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Rev. 0 | Page 10 of 16
AD8211
APPLICATION NOTES
OUTPUT LINEARITY
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 AD8211 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 24 shows
the input differential voltage vs. the corresponding output
voltage at different common modes.
Regardless of the common mode, the AD8211 provides a
correct output voltage when the input differential is at least
2 mV, which 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 to provide sufficient guardbands. The ability of the AD8211 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.
200
180
140
120
100
80
60
40
20
0
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IDEAL VOUT (mV)
VOUT (mV) @ VCM = 0V
VOUT (mV) @ VCM = 65V
0
1
2
3
4
5
6
7
8
9
06824-115
OUTPUT VOLTAGE (mV)
160
10
DIFFERENTIAL INPUT VOLTAGE (mV)
Figure 24. Gain Linearity Due to Differential and Common-Mode Voltage
Rev. 0 | Page 11 of 16
AD8211
APPLICATIONS INFORMATION
OVERCURRENT
DETECTION (<100ns)
HIGH-SIDE CURRENT SENSE WITH A LOW-SIDE
SWITCH
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 25). 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.
1
3
OUT
GND
VIN+
AD8211
VIN–
4
5
5
4
8
–IN
NC
VREG
+IN
VS
4
3
2
1
AD8214
1
3
2
1
3
OUT
GND
VIN+
AD8211
SHUNT
CLAMP
DIODE
VIN–
V+
4
5
5
4
INDUCTIVE
LOAD
BATTERY
5V
SWITCH
Figure 26. Battery-Referenced Shunt Resistor
BATTERY
LOW-SIDE CURRENT SENSING
SWITCH
In systems where low-side current sensing is preferred, the
AD8211 provides an integrated solution with great accuracy.
Ground noise is rejected, CMRR is typically higher than 90 dB,
and output linearity is not compromised, regardless of the input
differential voltage.
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Figure 25. Low-Side Switch
HIGH-SIDE CURRENT SENSING
In this configuration, the shunt resistor is referenced to the
battery. High voltage is 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 AD8211 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 is
useful in high current systems where fast shutdown in overcurrent conditions is essential.
1
3
2
1
3
OUT
GND
VIN+
AD8211
SWITCH
V+
VIN–
4
5
5
4
5V
INDUCTIVE
LOAD
CLAMP
DIODE
SHUNT
Figure 27. Ground-Referenced Shunt Resistor
Rev. 0 | Page 12 of 16
BATTERY
06824-026
5V
7
NC
INDUCTIVE
LOAD
CLAMP
DIODE
SHUNT
V+
6
GND
06824-025
2
06824-024
1
3
5
OUT
AD8211
OUTLINE DIMENSIONS
2.90 BSC
5
4
2.80 BSC
1.60 BSC
1
2
3
PIN 1
0.95 BSC
1.90
BSC
1.30
1.15
0.90
1.45 MAX
0.15 MAX
0.50
0.30
0.22
0.08
SEATING
PLANE
10°
5°
0°
0.60
0.45
0.30
COMPLIANT TO JEDEC STANDARDS MO-178-A A
Figure 28. 5-Lead Small Outline Transistor Package [SOT-23]
(RJ-5)
Dimensions shown in millimeters
ORDERING GUIDE
Model
AD8211YRJZ-R2 1
AD8211YRJZ-RL1
AD8211YRJZ-RL71
1
Temperature Range
−40°C to +125°C
−40°C to +125°C
−40°C to +125°C
Package Description
5-Lead SOT-23
5-Lead SOT-23
5-Lead SOT-23
Package Option
RJ-5
RJ-5
RJ-5
Branding
Y02
Y02
Y02
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Z = RoHS Compliant Part.
Rev. 0 | Page 13 of 16
AD8211
NOTES
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Rev. 0 | Page 14 of 16
AD8211
NOTES
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Rev. 0 | Page 15 of 16
AD8211
NOTES
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©2007 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D06824-0-7/07(0)
Rev. 0 | Page 16 of 16