High Resolution, Zero-Drift
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
Current Shunt Monitor
AD8217
FUNCTIONAL BLOCK DIAGRAM
R4
OUT
R3
Figure 1.
–IN
+IN
AD8217
R1
R2
LDO
GND
09161-001
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 additional 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.
Rev. A
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Anal og Devices for its use, nor for any infringements of patents or ot her
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.
AD8217
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
REVISION HISTORY
3/11—Rev. 0 to Rev. A
Changes to Features.......................................................................... 1
Changes to Figure 18........................................................................ 8
7/10—Revision 0: Initial Version
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
Rev. A | Page 2 of 16
AD8217
SPECIFICATIONS
T
= −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
OPR
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, T
Accuracy over Temperature ±0.35 % T
Gain vs. Temperature ±5 ppm/°C T
OPR
OPR
VOLTAGE OFFSET
Offset Voltage (RTI)1 ±250 μV 25°C
Over Temperature (RTI)1 ±300 μV T
Offset Drift ±100 nV/°C T
OPR
OPR
INPUT
Bias Current2 500 μA TA
800 μA T
OPR
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 T
OUTPUT
Output Voltage Range Low 0.01 V T
Output Voltage Range High 5 V T
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
OPR
4
A
4
A
Power regulated from common mode
Quiescent Current Over Temperature 800 μA Throughout input common mode
T
Power Supply Rejection Ratio (PSRR) 90 110 dB
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
Figure 8
flowing to the +IN pin is also the supply current to the internal LDO.
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
Figure 17 Figure 18
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
OPR
A
− 100 mV).
+IN
Rev. A | Page 3 of 16
AD8217
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 (T
Storage Temperature Range −65°C to +150°C
Output Short-Circuit Duration Indefinite
) −40°C to +125°C
OPR
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. A | Page 4 of 16
AD8217
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
+IN
1
AD8217
2
NC
TOP VIEW
3
NC
(Not to Scale)
GND
4
NC = NO CO N NECT
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.
–IN
8
7
NC
6
NC
OUT
5
09161-002
Rev. A | Page 5 of 16
AD8217
TYPICAL PERFORMANCE CHARACTERISTICS
40
38
36
34
(µV)
32
OSI
V
30
28
26
24
–40 –20 0 20 40 60 80 100 120 140
TEMPERATURE (°C)
Figure 3. Typical Input Offset vs. Temperature
140
130
120
110
100
90
CMRR (dB)
80
70
60
50
100 1000 10k 100k 1M
–40°C
+25°C
+125°C
FREQUENCY (Hz)
Figure 4. Typical CMRR vs. Frequency
500
9161-003
09161-004
30
27
24
21
18
15
12
MAGNITUDE ( d B)
9
6
3
0
1k 10k 100k 1M
Figure 6. Typical Small-Signal Bandwidth (V
FREQUENCY ( Hz )
= 200 mV p-p)
OUT
10
9
8
7
6
5
4
3
2
1
0
–1
TOTAL OUTPUT ERROR (%)
–2
–3
–4
–5
0 5 10 15 20 25 30 35 40 45 50
DIFFERENTIAL INPUT (mV)
Figure 7. Total Output Error vs. Differential Input Voltage
800
09161-006
09161-007
450
400
350
300
250
GAIN ERROR (ppm)
200
150
100
–40 –20 0 20 40 60 80 100 120
TEMPERATURE (°C)
Figure 5. Typical Gain Error vs. Temperature
09161-005
Rev. A | Page 6 of 16
700
600
500
400
300
200
INPUT BIAS CURRENT (µA)
100
0
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80
INPUT COMMON-MODE VOLTAGE (V)
+IN
–IN
Figure 8. Input Bias Current vs. Input Common-Mode Voltage
(Differential Input Voltage = 5 mV)
09161-008
AD8217
INPUT
INPUT
5mV/DIV
OUTPUT
100mV/DIV
1µs/DIV
Figure 9. Rise Time (Differential Input = 5 mV)
INPUT
100mV/DIV
09161-009
100mV/DIV
OUTPUT
2V/DIV
5µs/DIV
Figure 12. Fall Time (Differential Input = 200 mV)
INPUT
200mV/DIV
09161-012
OUTPUT
2V/DIV
5µs/DIV
Figure 10. Rise Time (Differential Input = 200 mV)
INPUT
5mV/DIV
OUTPUT
100mV/DIV
1µs/DIV
Figure 11. Fall Time (Differential Input = 5 mV)
OUTPUT
2V/DIV
09161-010
5µs/DIV
09161-013
Figure 13. Differential Overload Recovery, Rising
INPUT
200mV/DIV
OUTPUT
2V/DIV
09161-011
5µs/DIV
09161-014
Figure 14. Differential Overload Recovery, Falling
Rev. A | Page 7 of 16
AD8217
T
12.0
11.5
11.0
10.5
10.0
9.5
9.0
8.5
8.0
7.5
7.0
6.5
6.0
MAXIMUM OUT PUT SINK CURRENT ( mA)
5.5
5.0
–40 –30 –20 –10 0 10 20 30 40 50 60 70 80 90 100 110 120
TEMPERATURE (°C)
Figure 15. Maximum Output Sink Current vs. Temperature
9.5
9.0
8.5
8.0
7.5
7.0
6.5
6.0
5.5
5.0
4.5
MAXIMUM OUT PUT SOURCE CURRENT (m A)
4.0
–40
–30
0
102030405060708090
–20
–10
TEMPERATURE (°C)
Figure 16. Maximum Output Source Current vs. Temperature
5.010
5.000
4.990
4.980
4.970
4.960
4.950
4.940
4.930
4.920
OUTPUT VOLTAGE SWING FROM RAIL (V)
4.910
4.900
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
OUTPUT SO URCE CURRE NT (mA)
Figure 17. Output Voltage Range vs. Output Source Current
100
250
200
150
100
AGE RANGE FRO M GND (mV)
50
OUTPUT VOL
0
0 0.51.01.52.02.53.03.54.04.55.0
09161-015
OUTPUT SI NK CURRE NT (mA)
09161-018
Figure 18. Output Voltage Range From GND vs. Output Sink Current
INPUT
50V/DIV
OUTPUT
1V/DIV
110
120
130
140
150
09161-016
500ns/DIV
09161-019
Figure 19. Common-Mode Step Response, Rising
INPUT
50V/DIV
OUTPUT
1V/DIV
1µs/DIV
09161-017
09161-020
Figure 20. Common-Mode Step Response (Falling)
Rev. A | Page 8 of 16
AD8217
800
1200
700
1000
COUNT
800
600
400
200
0
–150–200
–100 –50 0 50 100 150 200
V
(µV)
OSI
09161-021
Figure 21. Input Offset Distribution
600
500
400
COUNT
300
200
100
0
–0.4 0.2
–0.2 0 0.4
OFFSET DRIFT (µV/°C)
Figure 23. Input Offset Drift Distribution
09161-023
1000
800
600
COUNT
400
200
0
–10 –5 0 5 10
GAIN DRIFT (ppm/°C)
09161-022
Figure 22. Gain Drift Distribution
Rev. A | Page 9 of 16
AD8217
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 voltages (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.
AD8217
I
LOAD
LOAD
4.5V
80V
TO
V
2
V
1
–IN
SHUNT
+IN
Figure 24. Simplified Schematic
R1
R2
LDO
GND
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.
R4
OUT
R3
09161-024
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 performance 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.
Rev. A | Page 10 of 16
AD8217
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.
200
180
160
140
120
100
80
OUTPUT (mV)
60
40
20
0
012345678910
Figure 25. Gain Linearity at Small Differential Inputs (V
DIFFERENTIAL INPUT (mV)
= 4.5 V to 80 V)
CM
9161-025
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.
Rev. A | Page 11 of 16
AD8217
V
A
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.
I
LOAD
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.
TTERY
B
I
MOTOR
4.5
TO
80V
Figure 26. Battery-Referenced Shunt Resistor
SHUNT
+IN
AD8217
GND
–IN
OUT
ADC
+IN
–IN
MOTOR
AD8217
OUT
GND
09161-026
Figure 27. High-Side Current Sensing in Motor Control
09161-027
Rev. A | Page 12 of 16
AD8217
OUTLINE DIMENSIONS
3.20
3.00
2.80
8
5
3.20
3.00
2.80
PIN 1
IDENTIFIER
0.95
0.85
0.75
0.15
0.05
COPLANARITY
1
0.65 BSC
0.10
COMPLIANT TO JEDEC STANDARDS MO-187-AA
Figure 28. 8-Lead Mini Small Outline Package [MSOP]
5.15
4.90
4.65
4
15° MAX
6°
0°
0.23
0.09
0.40
0.25
1.10 MAX
(RM-8)
Dimensions shown in millimeters
0.80
0.55
0.40
100709-B
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.
Rev. A | Page 13 of 16
AD8217
NOTES
Rev. A | Page 14 of 16
AD8217
NOTES
Rev. A | Page 15 of 16
AD8217
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)
Rev. A | Page 16 of 16
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