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Single-Supply 42 V System
Difference Amplifier
AD8205
FEATURES
Ideal for current shunt applications
High common-mode voltage range
−2 V to +65 V operating
−25 V to +75 V survival
Gain = 50
Wide operating temperature range: −40°C to +125°C
Bidirectional operation
Available in 8 Lead SOIC
Qualified for automotive applications
FUNCTIONAL BLOCK DIAGRAM
V+
6
+IN
8
5
OUT
–IN
1
AD8205
7
V
REF
1
3
NC
4
2
V
REF
2
04315-0-001
EXCELLENT AC AND DC PERFORMANCE
15 μV/°C offset drift
30 ppm/°C gain drift
80 dB CMRR dc to 20 kHz
NC = NO CONNECT
GND
Figure 1.
APPLICATIONS
High-side current sensing in:
Motor controls
Transmission controls
Diesel injection controls
Engine management
Suspension controls
Vehicle dynamic controls
DC-to-dc converters
GENERAL DESCRIPTION
The AD8205 is a single-supply difference amplifier for
amplifying small differential voltages in the presence of large
common-mode voltages. The operating input common-mode
voltage range extends from −2 V to +65 V. The typical single-
supply voltage is 5 V.
The AD8205 is offered in an 8-Lead SOIC package and rated for
operation from −40°C to +125°C.
Excellent dc performance over temperature keeps errors in the
measurement loop to a minimum. Offset drift is typically less
than 15 μV/°C, and gain drift is typically below 30 ppm/°C.
The output offset can be adjusted from 0.05 V to 4.8 V with a
5 V supply by using the V
REF
1 and V
REF
2 pins. With V
REF
1
attached to the V+ pin, and V
REF
2 attached to the GND pin, the
output is set at half scale. Attaching both pins to GND causes
the output to be unipolar, starting near ground. Attaching both
pins to V+ causes the output to be unipolar starting near V+.
Other offsets can be obtained by applying an external voltage to
the V
REF
1 and V
REF
2 pins.
Rev. B
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 ©2004–2010 Analog Devices, Inc. All rights reserved.
AD8205
TABLE OF CONTENTS
Features .............................................................................................. 1
Excellent AC and DC Performance................................................ 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 ........................................................................ 8
Output Offset Adjustment............................................................... 9
Unidirectional Operation .............................................................9
Ground Referenced Output .........................................................9
V+ Referenced Output .................................................................9
Bidirectional Operation................................................................9
External Reference Output........................................................ 10
Splitting the Supply .................................................................... 10
Splitting an External Reference ................................................ 10
Applications Information .............................................................. 11
High-Side Current Sense with a Low-Side Switch ................. 11
High-Side Current Sense with a High-Side Switch ............... 11
Outline Dimensions ....................................................................... 12
Ordering Guide .......................................................................... 12
Automotive Products ................................................................. 12
REVISION HISTORY
7/10—Rev. A to Rev. B
Changes to Features Section and General Description Section . 1
Delete Die Columns, Table 1 ........................................................... 3
Changes to Table 2 ............................................................................ 4
Changes to Figure 4 and Figure 6 ................................................... 6
Changes to Theory of Operation Section ...................................... 8
Changes to Ordering Guide .......................................................... 12
Added Automotive Products Section .......................................... 12
10/09—Rev. 0 to Rev. A
Changes to Output Resistance Parameter, Table 1 ....................... 3
Updated Outline Dimensions ....................................................... 12
Changes to Ordering Guide .......................................................... 12
4/04—Revision 0: Initial Version
Rev. B | Page 2 of 12
AD8205
SPECIFICATIONS
T
A
= operating temperature range, V
S
= 5 V, unless otherwise noted.
Table 1.
Parameter
GAIN
Initial
Accuracy
Accuracy Over Temperature
Gain vs. Temperature
VOLTAGE OFFSET
Offset Voltage (RTI)
1
Over Temperature (RTI)
1
Offset Drift
INPUT
Input Impedance
Differential
Common Mode
Input Voltage Range
Common-Mode Rejection
OUTPUT
Output Voltage Range
Output Resistance
DYNAMIC RESPONSE
Small Signal −3 dB Bandwidth
Slew Rate
NOISE
0.1 Hz to 10 Hz, RTI
Spectral Density, 1 kHz (RTI)
1
OFFSET ADJUSTMENT
Ratiometric Accuracy
4
Accuracy, RTO
Output Offset Adjustment Range
VREF Divider Resistor Values
POWER SUPPLY
Operating Range
Quiescent Current Over Temperature
Power Supply Rejection Ratio
Temperature Range
For Specified Performance
1
2
Test Conditions/Comments
Min
Typ
50
Max
Unit
V/V
%
%
ppm/°C
mV
mV
μV/°C
V
O
≥ 0.1 V dc, 25°C
Specified temperature range
±30
25°C
Specified temperature range
15
±1
±1.2
±2
±4.5
400
200
Common mode, continuous
Differential
2
25°C, f = dc to 20 kHz
3
Operating temperature range, f = dc to 20 kHz
3
R
L
= 25 kΩ
−2
78
76
0.05
2
50
0.5
20
0.5
Divider to supplies
Voltage applied to V
REF
1 and V
REF
2 in parallel
V
S
= 5 V
0.497
0.05
24
4.5
V
O
= 0.1 V dc
70
Operating temperature range
−40
+125
0.503
±2
4.8
40
5.5
2
100
86
80
4.8
65
kΩ
kΩ
V
mV
dB
dB
V
Ω
kHz
V/μs
μV p-p
μV/√Hz
V/V
mV/V
V
kΩ
V
mA
dB
°C
32
RTI is referred to input.
Input voltage range = ±50 mV with half-scale offset.
3
Source imbalance < 2 Ω.
4
The offset adjustment is ratiometric to the power supply when V
REF
1 and V
REF
2 are used as a divider between the supplies.
Rev. B | Page 3 of 12
AD8205
ABSOLUTE MAXIMUM RATINGS
Table 2.
Parameter
Supply Voltage
Continuous Input Voltage
Input Transient Survival
Differential Input Survival
Reverse Supply Voltage
Operating Temperature Range
Storage Temperature
Output Short-Circuit Duration
Rating
12.5 V
−25 V to +75 V
−30 V to +80 V
−25 V to +75 V
0.3 V
−40°C to +125°C
−65 to +150C
Indefinite
Stresses above those listed under Absolute Maximum Ratings
may cause permanent damage to the device. This is a stress
rating only and 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. B | Page 4 of 12
