Analog Devices AD8205 Datasheet

Single-Supply 42 V System

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

EXCELLENT AC AND DC PERFORMANCE

15 µV/°C offset drift
30 ppm/°C gain drift
80 dB CMRR dc to 20 kHz

APPLICATIONS

High-side current sensing in:

Motor controls

Transmission controls

Diesel injection controls

Engine management

Suspension controls

Vehicle dynamic controls

DC-to-dc converters

Difference Amplifier

FUNCTIONAL BLOCK DIAGRAM

V+

6

+IN

8

1

–IN

AD8205

4

NC

2

NC = NO CONNECT

GND

Figure 1.

AD8205

5

OUT

7

1

V

REF

3

2

V

REF

04315-0-001

GENERAL DESCRIPTION

The AD8205 is a single-supply difference amplifier for amplify­ing small differential voltages in the presence of large common­mode 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.

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.

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
tached to the V+ pin, and V

1 and V

REF

2 attached to the GND pin, the

REF

2 pins. With V

REF

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

1 and V

REF

2 pins.

REF

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: [phone] www.analog.com
Fax: [phone] © 2004 Analog Devices, Inc. All rights reserved.

REF

1 at-

AD8205

TABLE OF CONTENTS

Specifications..................................................................................... 3

Bidirectional Operation................................................................9

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

REVISION HISTORY

4/04—Revision 0: Initial Version

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

Rev. 0 | Page 2 of 12

AD8205

SPECIFICATIONS

TA = Operating Temperature Range, VS = 5 V, unless otherwise noted.

Table 1.

AD8205 SOIC AD8205 DIE

Parameter Conditions

Min Typ Max Min Typ Max

GAIN

Initial 50 50 V/V

Accuracy VO ≥ 0.1 V dc, 25°C ±1 ±1 %
Accuracy Over Temperature Specified Temperature Range ±1.2 ±1.3 %
Gain vs. Temperature ±30 ±30 ppm/°C

VOLTAGE OFFSET

Offset Voltage (RTI) 25°C ±2 ±2.5 mV
Over Temperature (RTI) Specified Temperature Range ±4.5 ±6 mV
Offset Drift 15 15 µV/°C

INPUT

Input Impedance

Differential 400 400 kΩ

Common Mode 200 200 kΩ
Input Voltage Range Common Mode, Continuous −2 65 −2 65 V
Differential1 100 100 mV
Common-Mode Rejection 25°C, f = DC to 20 kHz2 78 86 78 86 dB

Operating Temperature Range,
f = DC to 20 kHz

2

76 80 76 80 dB

OUTPUT

Output Voltage Range RL = 25 kΩ 0.05 4.8 0.05 4.8 V
Output Resistance 200 200 Ω

DYNAMIC RESPONSE

Small Signal −3 dB Bandwidth 50 50 kHz
Slew Rate 0.5 0.5 V/µs

NOISE

0.1 Hz to 10 Hz, RTI 20 20 µV p-p
Spectral Density, 1 kHz, RTI 0.5 0.5 µV/√Hz

OFFSET ADJUSTMENT

Ratiometric Accurancy3 Divider to Supplies 0.497 0.503 0.497 0.503 V/V
Accuracty, RTO

Voltage applied to V

1 and V

REF

REF

2

±2 ±2 mV/V

in Parallel
Output Offset Adjustment Range VS = 5 V 0.05 4.8 0.05 4.8 V
VREF Divider Resistor Values 24 32 40 24 32 40 kΩ

POWER SUPPLY

Operating Range 4.5 5.5 4.5 5.5 V
Quiescent Current Over Temperature VO = 0.1 V dc 2 2 mA
Power Supply Rejection Ratio 70 70 dB

Temperature Range

For Specified Performance Operating Temperature Range −40 +125 −40°C +150 °C

1

Input voltage range = ±50 mV with half-scale offset.

2

Source imbalance < 2 Ω.

3

The offset adjustment is ratiometric to the power supply when V

1 and V

REF

2 are used as a divider between the supplies.

REF

Unit

Rev. 0 | Page 3 of 12

AD8205

ABSOLUTE MAXIMUM RATINGS

Table 2.

Parameter Rating

Supply Voltage 12.5 V
Continuous Input Voltage −5 V to +68 V
Reverse Supply Voltage 0.3 V
Operating Temperature Range −40°C to +125°C
Storage Temperature −65 to +150C
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 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 pro­prietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy electro­static discharges. Therefore, proper ESD precautions are recommended to avoid performance degradation or
loss of functionality.

Rev. 0 | Page 4 of 12