High Resolution, Zero-Drift
Current Shunt Monitor
AD8217
Rev. A
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 ©2010–2011 Analog Devices, Inc. All rights reserved.
FEATURES
High common-mode voltage range
4.5 V to 80 V operating
0 V to 85 V survival
Buffered output voltage
Wide operating temperature range: −40°C to +125°C
Excellent ac and dc performance
±100 nV/°C typical offset drift
±100 μV typical offset
±5 ppm/°C typical gain drift
100 dB typical CMRR at dc
APPLICATIONS
High side current sensing
48 V telecom
Power management
Base stations
Unidirectional motor control
Precision high voltage current sources
FUNCTIONAL BLOCK DIAGRAM
LDO
R2
R1
AD8217
R4
R3
+IN
GND
–IN OUT
09161-001
Figure 1.
GENERAL DESCRIPTION
The AD8217 is a high voltage, high-resolution current shunt
amplifier. It features a set gain of 20 V/V, with a maximum
±0.35% gain error over the entire temperature range. The
buffered output voltage directly interfaces with any typical
converter. The AD8217 offers excellent common-mode rejection
from 4.5 V to 80 V, and includes an internal LDO, which directly
powers the device from the high voltage rail. Therefore, no addi-
tional supply is necessary, provided that the input common-mode
range is 4.5 V to 80 V. The AD8217 performs unidirectional
current measurements across a shunt resistor in a variety of
industrial and telecom applications including motor control,
battery management, and base station power amplifier bias
control.
The AD8217 offers breakthrough performance throughout the
−40°C to +125°C temperature range. It features a zero-drift
core, which leads to a typical offset drift of ±100 nV/°C
throughout the operating temperature and common-mode
voltage range. Special attention 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, and the typical input offset voltage is ±100 μV.
The AD8217 is offered in a 8-lead MSOP package and is
specified from −40°C to +125°C.
AD8217
Rev. A | Page 2 of 16
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications....................................................................................... 1
Functional Block Diagram .............................................................. 1
General Description......................................................................... 1
Revision History ............................................................................... 2
Specifications..................................................................................... 3
Absolute Maximum Ratings............................................................ 4
ESD Caution.................................................................................. 4
Pin Configuration and Function Descriptions............................. 5
Typical Performance Characteristics ............................................. 6
Theory of Operation ...................................................................... 10
Amplifier Core............................................................................ 10
Internal LDO............................................................................... 10
Application Notes........................................................................... 11
Output Linearity......................................................................... 11
Applications Information.............................................................. 12
High-Side Current Sensing....................................................... 12
Motor Control Current Sensing............................................... 12
Outline Dimensions ....................................................................... 13
Ordering Guide .......................................................................... 13
REVISION HISTORY
3/11—Rev. 0 to Rev. A
Changes to Features.......................................................................... 1
Changes to Figure 18........................................................................ 8
7/10—Revision 0: Initial Version
AD8217
Rev. A | Page 3 of 16
SPECIFICATIONS
TOPR = −40°C to +125°C, TA = 25°C, RL = 25 kΩ, input common-mode voltage (VCM = 4.5 V) (RL is the output load resistor), unless
otherwise noted.
Table 1.
Parameter Min Typ Max Unit Test Conditions/Comments
GAIN
Initial 20 V/V
Accuracy ±0.1 % VO ≥ 0.1 V dc, TA
Accuracy over Temperature ±0.35 % TOPR
Gain vs. Temperature ±5 ppm/°C TOPR
VOLTAGE OFFSET
Offset Voltage (RTI)1 ±250 μV 25°C
Over Temperature (RTI)1 ±300 μV TOPR
Offset Drift ±100 nV/°C TOPR
INPUT
Bias Current2 500 μA TA
800 μA TOPR
Common-Mode Input Voltage Range 4.5 80 V Common-mode continuous
Differential Input Voltage Range3 250 mV Differential input voltage
Common-Mode Rejection (CMRR) 90 100 dB TOPR
OUTPUT
Output Voltage Range Low 0.01 V TA4
Output Voltage Range High 5 V TA4
Output Impedance 2 Ω
DYNAMIC RESPONSE
Small Signal −3 dB Bandwidth 500 kHz
Slew Rate 1 V/μs
NOISE
0.1 Hz to 10 Hz, (RTI)1 2.3 μV p-p
Spectral Density, 1 kHz, (RTI)1 110 nV/√Hz
POWER SUPPLY
Operating Range 4.5 80 V Power regulated from common mode
Quiescent Current Over Temperature 800 μA Throughout input common mode
Power Supply Rejection Ratio (PSRR) 90 110 dB TOPR
TEMPERATURE RANGE
For Specified Performance −40 +125 °C
1 RTI = referred to input.
2 Refer to for further information on the input bias current. This current varies based on the input common-mode voltage. Additionally, the input bias current
flowing to the +IN pin is also the supply current to the internal LDO.
Figure 8
3 The differential input voltage is specified as 250 mV typical because the output is internally clamped to 5 V. This ensures the output voltage does not exceed 5 V and
can interface and not cause damage to any typical converter, regardless of the high voltage present at the inputs of the AD8217 (up to 80 V).
4 See and for further information on the output range of the AD8217 with various loads. The AD8217 output clamps to a maximum voltage of 5.6 V
when the voltage at pin +IN is greater than 5.6 V. When the voltage at +IN is less than 5.6 V, the output reaches a maximum value of (V+IN − 100 mV).
Figure 17 Figure 18
AD8217
Rev. A | Page 4 of 16
ABSOLUTE MAXIMUM RATINGS
Table 2.
Parameter Rating
Maximum Input Voltage ( +IN, −IN to GND) 0 V to 85 V
Differential Input Voltage (+IN to –IN) ±1 V
HBM (Human Body Model) ESD Rating ±2000 V
Operating Temperature Range (TOPR) −40°C to +125°C
Storage Temperature Range −65°C to +150°C
Output Short-Circuit Duration 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
AD8217
Rev. A | Page 5 of 16
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
+IN
1
NC
2
NC
3
GND
4
–IN
8
NC
7
NC
6
OUT
5
NC = NO CONNECT
AD8217
TOP VIEW
(Not to Scal e)
09161-002
Figure 2. Pin Configuration
Table 3. Pin Function Descriptions
Pin No. Mnemonic Description
1 +IN Noninverting Input. Supply pin to the internal LDO.
2 NC No Connect. No internal connection to pin.
3 NC No Connect. No internal connection to pin.
4 GND Ground.
5 OUT Output.
6 NC No Connect. No internal connection to pin.
7 NC No Connect. No internal connection to pin.
8 −IN Inverting Input.
AD8217
Rev. A | Page 6 of 16
TYPICAL PERFORMANCE CHARACTERISTICS
24
26
28
30
32
34
36
38
40
–40 –20 0 20 40 60 80 100 120 140
TEMPERATURE (° C)
V
OSI
(µV)
0
9161-003
Figure 3. Typical Input Offset vs. Temperature
50
60
70
80
90
100
110
120
130
140
100 1000 10k 100k 1M
FRE QUENC Y (Hz)
CMRR (dB)
–40°C
+25°C
+125°C
09161-004
Figure 4. Typical CMRR vs. Frequency
100
150
200
250
300
350
400
450
500
–40 –20 0 20 40 60 80 100 120
TEM PE RATURE (°C)
GAIN ERROR (ppm)
09161-005
Figure 5. Typical Gain Error vs. Temperature
0
3
6
9
12
15
18
21
24
27
30
1k 10k 100k 1M
FRE QUENC Y ( Hz )
MAG NITUDE ( dB)
09161-006
Figure 6. Typical Small-Signal Bandwidth (VOUT = 200 mV p-p)
–5
–4
–3
–2
–1
0
1
2
3
4
5
6
7
8
9
10
0 5 10 15 20 25 30 35 40 45 50
TOTAL O UTPUT E RROR (%)
DIFFERENTIAL INPUT (mV)
09161-007
Figure 7. Total Output Error vs. Differential Input Voltage
0
100
200
300
400
500
600
700
800
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80
INPUT COMMON-MODE VOLTAG E ( V)
INPUT BIAS CURRE NT ( µA)
+IN
–IN
09161-008
Figure 8. Input Bias Current vs. Input Common-Mode Voltage
(Differential Input Voltage = 5 mV)
AD8217
Rev. A | Page 7 of 16
INPUT
OUTPUT
5mV/DIV
1µs/DIV
100mV/DIV
09161-009
Figure 9. Rise Time (Differential Input = 5 mV)
INPUT
OUTPUT
100mV/DIV
2V/DIV
5µs/DIV
09161-010
Figure 10. Rise Time (Differential Input = 200 mV)
INPUT
OUTPUT
5mV/DIV
100mV/DIV
1µs/DIV
09161-011
Figure 11. Fall Time (Differential Input = 5 mV)
INPUT
OUTPUT
100mV/DIV
2V/DIV
5µs/DIV
09161-012
Figure 12. Fall Time (Differential Input = 200 mV)
INPUT
OUTPUT
200mV/DIV
2V/DIV
5µs/DIV
09161-013
Figure 13. Differential Overload Recovery, Rising
INPUT
OUTPUT
200mV/DIV
2V/DIV
5µs/DIV
09161-014
Figure 14. Differential Overload Recovery, Falling
AD8217
Rev. A | Page 8 of 16
5.0
5.5
6.0
6.5
7.0
7.5
8.0
8.5
9.0
9.5
10.0
10.5
11.0
11.5
12.0
–40 –30–20 –10 0 10 20 30 40 50 60 70 80 90 100 110120
TEMPERATURE (° C)
MAXI MUM OUTPUT SINK CURRENT ( mA)
09161-015
Figure 15. Maximum Output Sink Current vs. Temperature
5.0
5.5
4.0
4.5
6.0
6.5
7.0
7.5
8.0
8.5
9.0
9.5
–40
–30
–20
–10
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
150
TEMPERATURE (°C)
MAXI MUM OUTPUT S OURCE CURRENT (mA)
09161-016
Figure 16. Maximum Output Source Current vs. Temperature
4.900
4.910
4.920
4.930
4.940
4.950
4.960
4.970
4.980
4.990
5.000
5.010
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
OUT P UT SO URCE CURRE NT ( mA)
OUTPUT VOLTAGE SWI NG FROM RAIL (V)
09161-017
Figure 17. Output Voltage Range vs. Output Source Current
0
50
100
150
200
250
0 0.51.01.52.02.53.03.54.04.55.0
OUT P UT SI NK CURRENT (mA)
OUTPUT VOL
T
AGE RANG E FROM G ND ( mV )
09161-018
Figure 18. Output Voltage Range From GND vs. Output Sink Current
INPUT
OUTPUT
50V/DIV
1V/DIV
500ns/DIV
09161-019
Figure 19. Common-Mode Step Response, Rising
INPUT
OUTPUT
50V/DIV
1V/DIV
1µs/DIV
09161-020
Figure 20. Common-Mode Step Response (Falling)
AD8217
Rev. A | Page 9 of 16
1000
1200
600
800
200
400
0–150–200
09161-021
COUNT
VOSI (µV)
–100 –50 050 100 150 200
Figure 21. Input Offset Distribution
1000
800
600
200
0
–10 –5 0 5 10
09161-022
COUNT
GAIN DRIFT (ppm/°C)
400
Figure 22. Gain Drift Distribution
800
500
600
700
300
400
100
200
0–0.4 0.2
09161-023
COUNT
OFFSET DRIFT (µV/° C)
–0.2 00.4
Figure 23. Input Offset Drift Distribution
AD8217
Rev. A | Page 10 of 16
THEORY OF OPERATION
AMPLIFIER CORE
In typical applications, the AD8217 amplifies a small differential
input voltage generated by the load current flowing through
a shunt resistor. The AD8217 rejects high common-mode vol-
tages (up to 80 V) and provides a ground-referenced, buffered
output that interfaces with an analog-to-digital converter (ADC).
Figure 24 shows a simplified schematic of the AD8217.
LDO
LOAD
R2
R1
V
2
I
LOAD
V
1
AD8217
R4
R3
+IN
GND
–IN
SHUNT OUT
4.5V
TO
80V
09161-024
Figure 24. Simplified Schematic
The AD8217 is configured as a difference amplifier. The
transfer function is
OUT = (R4/R1) × (V1 − V2)
Resistors R4 and R1 are matched to within 0.01% and have
values of 1.5 MΩ and 75 kΩ, respectively, meaning an input
to output total gain of 20 V/V for the AD8217.
The AD8217 accurately amplifies the input differential signal,
rejecting high voltage common modes ranging from 4.5 V to 80 V.
The main amplifier uses a novel zero-drift architecture, providing
the end user with an extremely stable part over temperature.
The offset drift is typically less than ±100 nV/°C. This perfor-
mance leads to optimal accuracy and dynamic range.
INTERNAL LDO
The AD8217 includes an internal LDO, which allows the device
to power directly from the common-mode voltage at the inputs.
No additional standalone supply is necessary, provided that the
common-mode voltage at the +IN pin is at least 4.5 V and up to
80 V. Once the common-mode voltage is above 5.6 V, the LDO
output reaches its maximum value, that is 5.6 V. This is also the
maximum output voltage range of the AD8217. Because the
AD8217 output typically interfaces with a converter, the 5.6 V
maximum output range ensures the ADC input is not damaged
due to excessive overvoltage.
The input bias current flowing through Pin +IN powers the
internal LDO and, therefore, doubles as the supply current
for the AD8217. This current varies depending on the input
common-mode voltage. See Figure 8 for additional information.
AD8217
Rev. A | Page 11 of 16
APPLICATION NOTES
OUTPUT LINEARITY
In all current sensing applications 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 AD8217
maintains a very high input-to-output linearity even when the
differential input voltage is very small.
0
20
40
60
80
100
120
140
160
180
200
012345678910
DIFFERENTIAL INPUT (mV)
OUTPUT (mV)
0
9161-025
Figure 25. Gain Linearity at Small Differential Inputs (VCM = 4.5 V to 80 V)
Regardless of the common mode, the AD8217 provides a
correct output voltage when the input differential is at least
1 mV. The ability of the AD8217 to work with very small
differential inputs, regardless of the common-mode voltage,
allows for optimal dynamic range, accuracy, and flexibility in
any current sensing application.
AD8217
Rev. A | Page 12 of 16
APPLICATIONS INFORMATION
HIGH-SIDE CURRENT SENSING
In this configuration, the shunt resistor is referenced to the
battery (see Figure 26). High voltage is present at the inputs
of the current sense amplifier. When the shunt is battery
referenced, the AD8217 produces a linear ground-referenced
analog output. The AD8217 includes an internal LDO, which
allows the part to be powered from the high voltage rail, with
no need for an additional standalone supply.
+IN
I
LOAD
SHUNT
GND
–IN
ADC
4.5
V
TO
80V
AD8217
OUT
09161-026
Figure 26. Battery-Referenced Shunt Resistor
MOTOR CONTROL CURRENT SENSING
The AD8217 is a practical, accurate solution for high-side
current sensing in motor control applications. In cases where
the shunt resistor is referenced to battery and the current
flowing is unidirectional (as shown in Figure 27), the AD8217
monitors the current with no additional supply pin necessary.
+IN
GND
–IN
B
A
TTE
R
Y
MOTOR
I
MOTOR
AD8217
OUT
09161-027
Figure 27. High-Side Current Sensing in Motor Control
AD8217
Rev. A | Page 13 of 16
OUTLINE DIMENSIONS
COMPLIANT TO JEDEC STANDARDS MO-187-AA
100709-B
6°
0°
0.80
0.55
0.40
4
8
1
5
0.65 BSC
0.40
0.25
1.10 MAX
3.20
3.00
2.80
COPLANARITY
0.10
0.23
0.09
3.20
3.00
2.80
5.15
4.90
4.65
PIN 1
IDENTIFIER
15° MAX
0.95
0.85
0.75
0.15
0.05
Figure 28. 8-Lead Mini Small Outline Package [MSOP]
(RM-8)
Dimensions shown in millimeters
ORDERING GUIDE
Model1 Temperature Range Package Description Package Option Branding
AD8217BRMZ −40°C to +125°C 8-Lead Mini Small Outline Package (MSOP) RM-8 Y2L
AD8217BRMZ-RL −40°C to +125°C 8-Lead Mini Small Outline Package (MSOP) RM-8 Y2L
AD8217BRMZ-R7 −40°C to +125°C 8-Lead Mini Small Outline Package (MSOP) RM-8 Y2L
1 Z = RoHS Compliant Part.
AD8217
Rev. A | Page 14 of 16
NOTES
AD8217
Rev. A | Page 15 of 16
NOTES
AD8217
Rev. A | Page 16 of 16
NOTES
©2010–2011 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D09161-0-3/11(A)
