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
−5 V to +68 V survival
Gain = 50
Wide operating temperature range
Die: −40°C to +150°C
8-lead SOIC:
−40°C
to +125°C
Adjustable offset
Available in SOIC and die form
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 amplify-
ing 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 die and packaged form. The operating
temperature range for the die is 25°C higher (up to 150°C) than
the packaged part to enable the user to apply the AD8205 in
high temperature applications.
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 at-
tached 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. 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: 781.326.8703
© 2004 Analog Devices, Inc. All rights reserved.
AD8205
TABLE OF CONTENTS
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..................................................................................... 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
REVISION HISTORY
4/04—Revision 0: Initial Version
Rev. 0 | 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)
Over Temperature (RTI)
Offset Drift
INPUT
Input Impedance
Differential
Common Mode
Input Voltage Range
Common-Mode Rejection
Conditions
AD8205 SOIC
Min
Typ Max
50
V
O
≥ 0.1 V dc, 25°C
Specified Temperature Range
±30
25°C
Specified Temperature Range
15
±2
±4.5
15
±1
±1.2
±30
±2.5
±6
AD8205 DIE
Min
Typ Max
50
±1
±1.3
Unit
V/V
%
%
ppm/°C
mV
mV
µV/°C
400
200
Common Mode, Continuous
Differential
1
25°C, f = DC to 20 kHz
2
Operating Temperature Range,
f = DC to 20 kHz
2
R
L
= 25 kΩ
−2
78
76
100
86
80
65
−2
78
76
400
200
65
100
86
80
kΩ
kΩ
V
mV
dB
dB
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
OFFSET ADJUSTMENT
Ratiometric Accurancy
3
Accuracty, 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
0.05
200
50
0.5
20
0.5
4.8
0.05
200
50
0.5
20
0.5
4.8
V
Ω
kHz
V/µs
µV p-p
µV/√Hz
Divider to Supplies
Voltage applied to V
REF
1 and V
REF
2
in Parallel
V
S
= 5 V
0.497
0.503
±2
4.8
40
5.5
2
0.497
0.503
±2
4.8
40
5.5
2
V/V
mV/V
V
kΩ
V
mA
dB
°C
0.05
24
4.5
32
0.05
24
4.5
70
32
V
O
= 0.1 V dc
70
Operating Temperature Range
−40
+125
−40°C
+150
1
2
Input voltage range = ±50 mV with half-scale offset.
Source imbalance < 2 Ω.
3
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. 0 | Page 3 of 12
AD8205
ABSOLUTE MAXIMUM RATINGS
Table 2.
Parameter
Supply Voltage
Continuous Input Voltage
Reverse Supply Voltage
Operating Temperature Range
Storage Temperature
Output Short-Circuit Duration
Rating
12.5 V
−5 V to +68 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
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on
the human body and test equipment and can discharge without detection. Although this product features pro-
prietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy electro-
static discharges. Therefore, proper ESD precautions are recommended to avoid performance degradation or
loss of functionality.
Rev. 0 | Page 4 of 12
AD8205
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
–IN
1
GND
2
8
+IN
NC = NO CONNECT
Figure 3. Pin Configuration
Table 3. Pin Function Descriptions
Pin No.
1
2
3
4
5
6
7
8
Mnemonic
−IN
GND
V
REF
2
NC
OUT
V+
V
REF
1
+IN
X
−206
−447
−432
N/A
444
444
456
203
Y
508
57
−457
N/A
−472
−203
434
509
Figure 2. Metallization Diagram
04315-0-002
Die size is 1170 µm by 1280 µm.
Die thickness is 13 mil.
Minimum passivation opening (minimum bond pad size) is
92 µm × 92 µm.
Passivation type is 8KA USG (Oxide) + 10KA Oxynitride.
Bond pad metal composition is 98.5% Al, 1% Si, and 0.5% Cu.
Backside potential is V+.
Rev. 0 | Page 5 of 12
04315-0-026
V
REF
1
TOP VIEW
V
REF
2
3
6
V+
(Not to Scale)
NC
4
5
OUT
7
AD8205
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