ANALOG DEVICES AD8207 Service Manual

Zero-Drift, High Voltage,

FEATURES

Ideal for current shunt applications
EMI filters included
1 μV/°C maximum input offset drift
High common-mode voltage range

−4 V to +65 V operating (5 V supply)

−4 V to +35 V operating (3.3 V supply)

−25 V to +75 V survival

Gain = 20 V/V

3.3 V to 5.5 V supply range
Wide operating temperature range: −40°C to +125°C
Bidirectional current monitoring
<500 nV/°C typical offset drift
<10 ppm/°C typical gain drift
>90 dB CMRR dc to 10 kHz
Qualified for automotive applications

APPLICATIONS

High-side current sensing in

Motor control
Solenoid control
Engine management
Electric power steering
Suspension control
Vehicle dynamic control
DC-to-DC converters

Bidirectional Difference Amplifier

AD8207

FUNCTIONAL BLOCK DIAGRAM

V+

RANGE

+IN

–IN

AD8207

REF

GND

Figure 1.

ZERO
DRIFT

OUT

V

REF

V

REF

1

2

09160-001

GENERAL DESCRIPTION

The AD8207 is a single-supply difference amplifier ideal for
amplifying small differential voltages in the presence of large
common-mode voltage. The operating input common-mode
voltage range extends from −4 V to +65 V with a 5 V supply.
The AD8207 works with a single-supply voltage of 3.3 V to 5 V,
and is ideally suited to withstand large input PWM common­mode voltages, typical in solenoid and motor control applications.

The AD8207 is available in an 8-lead SOIC package. Excellent
dc performance over temperature keeps errors in the mea­surement loop to a minimum. Offset drift is typically less
than 500 nV/°C, and gain drift is typically below 10 ppm/°C.

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.

The AD8207 is ideal for bidirectional current sensing
applications. It features two reference pins,V

1 and V

REF

that allow the user to easily offset the output of the device to
any voltage within the supply range. With V
V+ pin and V

2 attached to the GND pin, the output is set at

REF

1 attached to the

REF

half scale. Attaching both pins to GND causes the output to
be unipolar, starting near ground. Attaching both pins to V+

ca

uses the output to be unipolar starting near V+. Other output
offsets are achieved by applying an external low impedance
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] © 2010 Analog Devices, Inc. All rights reserved.

REF

2,

AD8207

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

Power Supply Adjustment ............................................................. 11

3.3 V to 4.5 V Supply Operation .............................................. 11

4.5 V to 5.5 V Supply Operation .............................................. 11

Output Offset Adjustment ............................................................ 12

Unidirectional Operation .......................................................... 12

Bidirectional Operation ............................................................. 12

External Referenced Output ..................................................... 13

Splitting the Supply .................................................................... 13

Splitting an External Reference ................................................ 13

Applications Information .............................................................. 14

Motor Control ............................................................................. 14

Solenoid Control ........................................................................ 15

Outline Dimensions ....................................................................... 16

Ordering Guide .......................................................................... 16

Automotive Products ................................................................. 16

REVISION HISTORY

7/10—Revision 0: Initial Version

Rev. 0 | Page 2 of 16

AD8207

SPECIFICATIONS

T

= −40°C to +125°C, V+ = 5 V or 3.3 V, unless otherwise noted.

OPR

Table 1.

Parameter Min Typ Max Unit Test Conditions/Comments

GAIN

Initial 20 V/V

Accuracy over Temperature −0.3 +0.3 % T
Gain vs. Temperature −15 0 ppm/°C T

VOLTAGE OFFSET

Offset Voltage (RTI)1 ±100 µV 25°C
Over Temperature (RTI)1 ±400 µV T
Offset Drift −1 +1 V/°C T

INPUT

Input Impedance

Differential 240 kΩ
Common Mode 126 kΩ

Input Voltage Range −4 +65 V Common mode, continuous, V+ = 5 V, T

−4 +35 V Common mode continuous, V+ = 3.3 V, T
250 mV Differential2, V+ = 5 V
Common-Mode Rejection (CMRR) 80 90 dB T

OUTPUT

Output Voltage Range 0.02 V+ − 0.05 V RL = 25 kΩ, T
Output Resistance 2 Ω

DYNAMIC RESPONSE

Small-Signal −3 dB Bandwidth 150 kHz T
Slew Rate 1 V/µs

NOISE

0.1 Hz to 10 Hz, (RTI)1 20 µV p-p
Spectral Density, 1 kHz, (RTI)1 0.6 µV/√Hz

OFFSET ADJUSTMENT

Ratiometric Accuracy3 0.497 0.503 V/V Divider to supplies, T
Accuracy (RTO)4 ±3 mV/V

Output Offset Adjustment Range 0.02 V+ − 0.05 V T
V

Input Voltage Range

REF

5

0.0 V+ V

VREF Divider Resistor Values 100 kΩ

POWER SUPPLY

Operating Range 4.5 5.5 V RANGE (Pin 4) connected to GND

3.3 4.5 V RANGE (Pin 4) connected to V+7
Quiescent Current over Temperature 2.5 mA VO = 0.1 V dc
Power Supply Rejection Ratio (PSRR) 80 dB

TEMPERATURE RANGE

For Specified Performance −40 +125 °C

1

RTI = referred to input.

2

Input voltage range = ±125 mV with half-scale offset. The input differential range also depends on the supply voltage. The maximum input differential range can be

calculated by V+/20.

3

The offset adjustment is ratiometric to the power supply when V

4

RTO = referred to output.

5

The reference pins should be driven with a low impedance voltage source to maintain the specified accuracy of the AD8207.

6

With a 4.5 V to 5.5 V supply, the RANGE pin should be tied low. In this mode, the common-mode range of the AD8207 is −4 V to +65 V.

7

With a 3.3 V to 4.5 V supply, the RANGE pin should be tied to V+. In this mode, the common-mode range of the AD8207 is −4 V to +35 V. If a 4.5 V supply is used, the

user can tie RANGE high or low depending on the common-mode range needed in the application.

1 and V

REF

2 are used as a divider between the supplies.

REF

OPR

OPR

OPR

OPR

, f = dc to 20 kHz

OPR

OPR

OPR

Voltage applied to V
T

OPR

OPR

OPR

1 and V

REF

OPR

OPR

2 in parallel,

REF

6

Rev. 0 | Page 3 of 16

AD8207

ABSOLUTE MAXIMUM RATINGS

Table 2.

Parameter Rating

Supply Voltage 12.5 V
Continuous Input Voltage −25 V to +75 V
Input Transient Survival −30 V to +80 V
Differential Input Voltage −25 V to +75 V
Reverse Supply Voltage 0.3 V
Operating Temperature Range −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 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. 0 | Page 4 of 16

AD8207

PIN CONFIGURATION AND FUNCTION DESCRIPTIONS

–IN

1

2

2

3

4

AD8207

TOP VIEW

(Not to Scale)

GND

V

REF

RANGE

Figure 2. Pin Configuration

Table 3. Pin Function Descriptions

Pin No. Mnemonic Description

1 −IN Negative Input.
2 GND Ground Pin.
3 V

2 Reference Input.

REF

4 RANGE Range Pin. This pin switches between 4.5 V to 5.5 V and 3.3 V to 4.5 V supply operation.
5 OUT Output.
6 V+ Supply Pin.
7 V

1 Reference Input.

REF

8 +IN Positive Input.

+IN

8

V

1

7

REF

V+

6

OUT

5

09160-002

Rev. 0 | Page 5 of 16