Datasheet AD8206 Datasheet (Analog Devices)

Single-Supply 42 V System

Preliminary Technical Data

FEATURES

Ideal for current shunt applications
High common-mode voltage range

−2 V to +65 V operating

−5 V to +68 V survival
Gain = 20
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

AD8206

4

NC

2

NC = NO CONNECT

GND

Figure 1.

AD8206

5

OUT

7

1

V

REF

3

2

V

REF

04953-001

GENERAL DESCRIPTION

The AD8206 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 AD8206 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 AD8206 in
high temperature applications.

Rev. PrA

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

REF

tached to the V+ pin, and V

1 and V

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

REF

2 pins.

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-

AD8206 Preliminary Technical Data

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

6/04—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. PrA | Page 2 of 12

Preliminary Technical Data AD8206

SPECIFICATIONS

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

Table 1.

AD8206 SOIC AD8206 DIE

Parameter Conditions

Min Typ Max Min Typ Max

GAIN

Initial 20 20 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
Differential
Common-Mode Rejection 25°C, f = DC to 20 kHz

Operating Temperature Range,
f = DC to 20 kHz

1

2

250 250 mV
78 86 78 86 dB
76 80 76 80 dB

2

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 Accuracy
Accuracy, RTO

3

Divider to Supplies 0.497 0.503 0.497 0.503 V/V
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 = ±125 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. PrA | Page 3 of 12

AD8206 Preliminary Technical Data

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. PrA | Page 4 of 12

Preliminary Technical Data AD8206

PIN CONFIGURATION AND FUNCTION DESCRIPTIONS

–IN

Figure 2. Metallization Diagram

04953-002

1

AD8206

2

TOP VIEW

2

3

(Not to Scale)

NC

4

NC = NO CONNECT

V

GND

REF

Figure 3. Pin Configuration

Table 3. Pin Function Descriptions

Pin No. Mnemonic X Y

1 −IN −206 508
2 GND −447 57
3 V

2 −432 −457

REF

4 NC N/A N/A
5 OUT 444 −472
6 V+ 444 −203
7 V

1 456 434

REF

8 +IN 203 509

Die size is 1170 µm by 1280 µm.

+IN

8

V

1

7

REF

V+

6

OUT

5

04953-003

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. PrA | Page 5 of 12

AD8206 Preliminary Technical Data

TYPICAL PERFORMANCE CHARACTERISTICS

Figure 4. Typical Offset Drift

Figure 5. CMR vs. Frequency

Figure 7. Typical Small Signal Bandwidth (V

Figure 8. Rise/Fall Time

= 200 mV p-p)

OUT

Figure 6. Gain Drift

Figure 9. Differential Overload Recovery (Falling)

Rev. PrA | Page 6 of 12

Preliminary Technical Data AD8206

Figure 10. Differential Overload Recovery (Rising)

Figure 11. Settling Time

Figure 12. Common-Mode Response

Rev. PrA | Page 7 of 12

AD8206 Preliminary Technical Data

–

THEORY OF OPERATION

The AD8206 is a single-supply difference amplifier that uses a
unique architecture to accurately amplify small differential cur­rent shunt voltages in the presence of rapidly changing common­mode voltages. It is offered in both packaged and die form.

In typical applications, the AD8206 is used to measure current
by amplifying the voltage across a current shunt placed across
the inputs.

The gain of the AD8206 is 20 V/V, with an accuracy of 1.2%.
This accuracy is guaranteed over the operating temperature
range of −40°C to +125°C. The die temperature range is −40°C
to +150°C with a guaranteed gain accuracy of 1.3%.

The input offset is less than 2 mV referred to the input at 25°C,
and 4.5 mV maximum referred to the input over the full operat­ing temperature range for the packaged part. The die input off­set is less than 6 mV referred to the input over the die operating
temperature range.

The AD8206 operates with a single supply from 4.5 V to 10 V (ab­solute maximum = 12.5 V). The supply current is less than 2 mA.

High accuracy trimming of the internal resistors allows the
AD8206 to have a common-mode rejection ratio better than
78 dB from dc to 20 kHz. The common-mode rejection ratio
over the operating temperature is 76 dB for both the die and
packaged part.

The output offset can be adjusted from 0.05 V to 4.8 V (V+ =
5 V) for unipolar and bipolar operation.

The AD8206 consists of two amplifiers (A1 and A2), a resistor
network, small voltage reference, and a bias circuit (not shown),
see Figure 13.

The set of input attenuators preceding A1 consist of R

, which reduce the common-mode voltage to match the input

R

C

, RB, and

A

voltage range of A1. The two attenuators form a balanced bridge
network. When the bridge is balanced, the differential voltage
created by a common-mode voltage is 0 V at the inputs of A1.
The input attenuation ratio is 1/16.7. The combined series resis­tance of R

, RB, and RC is approximately 200 kΩ ± 20%.

A

By attenuating the voltages at Pin 1 and Pin 8, the A1 amplifier
inputs are held within the power supply range, even if Pin 1 and
Pin 8 exceed the supply or fall below common (ground). A ref­erence voltage of 250 mV biases the attenuator above ground.
This allows the amplifier to operate in the presence of negative
common-mode voltages.

The input network also attenuates normal (differential) mode
voltages. A1 amplifies the attenuated signal by 26. The input
and output of this amplifier are differential to maximize the ac
common-mode rejection.

A2 converts the differential voltage from A1 into a single-ended
signal and provides further amplification. The gain of this sec­ond stage is 12.86.

The reference inputs, V

1 and V

REF

2, are tied through resistors

REF

to the positive input of A2, which allows the output offset to be
adjusted anywhere in the output operating range. The gain is
1 V/V from the reference pins to the output when the reference
pins are used in parallel. The gain is 0.5 V/V when they are used
to divide the supply.

The ratios of Resistors R

, RB, RC, RD, and RF are trimmed to a

A

high level of precision to allow the common-mode rejection
ratio to exceed 80 dB. This is accomplished by laser trimming
the resistor ratio matching to better than 0.01%.

The total gain of 50 is made up of the input attenuation of
1/16.7 multiplied by the first stage gain of 26 and the second
stage gain of 12.86.

The output stage is Class A with a PNP pull-up transistor and a
300 µA current sink pull-down.

+IN

IN

R

ARA

A1

RBR

RCR

250mV

GND

B

C

RFRFRDR

AD8206

Figure 13. Simplified Schematic

RER

D

F

A2

V

OUT

V

1

REF

R

REF

R

REF

V

2

REF

04953-013

Rev. PrA | Page 8 of 12

Preliminary Technical Data AD8206

OUTPUT OFFSET ADJUSTMENT

The output of the AD8206 can be adjusted for unidirectional or
bidirectional operation.

UNIDIRECTIONAL OPERATION

Unidirectional operation allows the AD8206 to measure cur­rents through a resistive shunt in one direction. The basic
modes for unidirectional operation are ground referenced
output mode and V+ referenced output mode.

In the case of unidirectional operation, the output could be set
at the negative rail (near ground) or at the positive rail (near
V+) when the differential input is 0 V. The output moves to the
opposite rail when a correct polarity differential input voltage is
applied. In this case, full scale is approximately 250 mV. The
required polarity of the differential input depends on the output
voltage setting. If the output is set at the positive rail, the input
polarity needs to be negative to move the output down. If the
output is set at ground, the polarity is positive to move the
output up.

GROUND REFERENCED OUTPUT

When using the AD8206 in this mode, both reference inputs are
tied to ground, which causes the output to sit at the negative rail
when there are zero differential volts at the input (see Figure 14).

GND

V+

OUT

1

V

REF

2

V

REF

04953-014

O

+IN

–IN

AD8206

NC

NC = NO CONNECT

Figure 14. Ground Referenced Output

Table 4. V+ = 5 V

VIN (Referred to −IN) V

0 V 0.05 V
250 mV 4.8 V

V+ REFERENCED OUTPUT

This mode is set when both reference pins are tied to the posi­tive supply. It is typically used when the diagnostic scheme
requires detection of the amplifier and the wiring before power
is applied to the load (see Figure 15).

GND

V+

OUT

1

V

REF

2

V

REF

04953-015

+IN

–IN

AD8206

NC

NC = NO CONNECT

Figure 15. V+ Referenced Output

Table 5. V+ = 5 V

VIN (Referred to −IN) V

O

0 V 4.8 V
250 mV 0.05 V

BIDIRECTIONAL OPERATION

Bidirectional operation allows the AD8206 to measure currents
through a resistive shunt in two directions.

In this case, the output is set anywhere within the output range.
Typically, it is set at half-scale for equal range in both directions.
In some cases, however, it is set at a voltage other than half-scale
when the bidirectional current is nonsymmetrical.

Table 6. V+ = 5 V, V

VIN (Referred to −IN) V

+100 mV 4.5 V

−100 mV 0.5 V

Adjusting the output is accomplished by applying voltage(s) to
the reference inputs.

1 and V

V

REF

REF

internal offset node. There is no operational difference between
the pins.

= 2.5 with VIN = 0 V

O

O

2 are tied to internal resistors that connect to an

Rev. PrA | Page 9 of 12

AD8206 Preliminary Technical Data

EXTERNAL REFERENCE OUTPUT

Tying both pins together and to a reference produces an output
at the reference voltage when there is no differential input (see
Figure 16). The output moves down from the reference voltage
when the input is negative relative to the −IN pin and up when
the input is positive relative to the −IN pin.

GND

V+

OUT

1

V

REF

2

V

REF

2.5V

VOLTAGE
REFERENCE

04953-016

+IN

–IN

AD8206

NC

NC = NO CONNECT

Figure 16. External Reference Output

SPLITTING THE SUPPLY

By tying one reference pin to V+ and the other to the ground
pin, the output is set at half of the supply when there is no
differential input (see Figure 17). The benefit is that no external
reference is required to offset the output for bidirectional
current measurement. This creates a midscale offset that is
ratiometric to the supply, which means that if the supply increases
or decreases, the output remains at half the supply. For example, if
the supply is 5.0 V, the output is at half scale or 2.5 V. If the supply
increases by 10% (to 5.5 V), the output goes to 2.75 V.

+IN

–IN

AD8206

NC

NC = NO CONNECT

Figure 17. Split Supply

SPLITTING AN EXTERNAL REFERENCE

In this case, an external reference is divided by 2 with an
accuracy of approximately 0.5% by connecting one V
ground and the other V

+IN

–IN

AD8206

NC

NC = NO CONNECT

Figure 18. Split External Reference

pin to the reference (see Figure 18).

REF

GND

V+

OUT

1

V

REF

V

2

GND

V+

REF

04953-017

pin to

REF

OUT

V

1

REF

V

2

REF

5V

VOLTAGE
REFERENCE

04953-018

Rev. PrA | Page 10 of 12

Preliminary Technical Data AD8206

Y

Y

APPLICATIONS

A typical application for the AD8206 is high-side measurement
of a current through a solenoid for PWM control of the sole­noid opening. Typical applications include hydraulic transmis­sion control and diesel injection control.

Two typical circuit configurations are used for this type of
application.

HIGH-SIDE CURRENT SENSE WITH A LOW-SIDE SWITCH

In this case, the PWM control switch is ground referenced. An
inductive load (solenoid) is tied to a power supply. A resistive
shunt is placed between the switch and the load (see Figure 19).
An advantage of placing the shunt on the high side is that the
entire current, including the re-circulation current, can be
measured since the shunt remains in the loop when the switch
is off. In addition, diagnostics can be enhanced because shorts
to ground can be detected with the shunt on the high side.

In this circuit configuration, when the switch is closed, the
common-mode voltage moves down to near the negative rail.
When the switch is opened, the voltage reversal across the
inductive load causes the common-mode voltage to be held one
diode drop above the battery by the clamp diode.

5V

INDUCTIVE
LOAD

+IN V

1 +VSOUT

REF

AD8206

–IN GND V

REF

2 NC

BATTER

42V

CLAMP
DIODE

SWITCH

SHUNT

When using a high-side switch, the battery voltage is connected
to the load when the switch is closed, causing the common­mode voltage to increase to the battery voltage. In this case,
when the switch is opened, the voltage reversal across the
inductive load causes the common-mode voltage to be held one
diode drop below ground by the clamp diode.

5V

SWITCH

BATTER

42V

SHUNT

CLAMP
DIODE

+IN V

–IN GND V

INDUCTIVE
LOAD

1 +VSOUT

REF

AD8206

2 NC

REF

NC = NO CONNECT

04953-020

Figure 20. High-Side Switch

Another typical application for the AD8206 is as part of the
control loop in H-bridge motor control. In this case, the
AD8206 is placed in the middle of the H-bridge (see Figure 21)
so that it can accurately measure current in both directions by
using the shunt available at the motor. This is a better solution
than a ground referenced op amp because ground is not typi­cally a stable reference voltage in this type of application. This
instability in the ground reference causes the measurements
that could be made with a simple ground referenced op amp to
be inaccurate.

The AD8206 measures current in both directions as the
H-bridge switches and the motor changes direction. The output
of the AD8206 is configured in an external reference bidirec­tional mode, see the Output Offset Adjustment section.

NC = NO CONNECT

Figure 19. Low-Side Switch

HIGH-SIDE CURRENT SENSE WITH A HIGH-SIDE SWITCH

This configuration minimizes the possibility of unexpected
solenoid activation and excessive corrosion (see Figure 20). In
this case, both the switch and the shunt are on the high side.
When the switch is off, this removes the battery from the load,
which prevents damage from potential shorts to ground, while
still allowing the recirculating current to be measured and pro­viding for diagnostics. Removing the power supply from the
load for the majority of the time minimizes the corrosive effects
that could be caused by the differential voltage between the load

04953-019

CONTROLLER

5V

2.5V

04953-021

MOTOR

SHUNT

+IN V

1 +VSOUT

REF

AD8206

–IN GND V

5V

2 NC

REF

NC = NO CONNECT

Figure 21. Motor Control Application

and ground.

Rev. PrA | Page 11 of 12

AD8206 Preliminary Technical Data

Y

OUTLINE DIMENSIONS

5.00 (0.1968)

4.80 (0.1890)

4.00 (0.1574)

3.80 (0.1497)

85

6.20 (0.2440)

5.80 (0.2284)

41

1.27 (0.0500)
BSC

0.25 (0.0098)

0.10 (0.0040)

COPLANARIT

0.10

CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS
(IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR
REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN

SEATING

PLANE

COMPLIANT TO JEDEC STANDARDS MS-012AA

1.75 (0.0688)

1.35 (0.0532)

0.51 (0.0201)

0.31 (0.0122)

0.25 (0.0098)

0.17 (0.0067)

0.50 (0.0196)

0.25 (0.0099)

8°

1.27 (0.0500)

0°

0.40 (0.0157)

× 45°

Figure 22. 8-Lead Standard Small Outline Package [SOIC]

Narrow Body

(R-8)

Dimensions shown in millimeters and (inches)

ORDERING GUIDE

Models Temperature Range Package Description Package Option

AD8206YR −40°C to +125°C 8-Lead SOIC R-8
AD8206YR-REEL −40°C to +125°C 8-Lead SOIC, 13” Tape and Reel R-8
AD8206YR-REEL7 −40°C to +125°C 8-Lead SOIC, 7” Tape and Reel R-8
AD8206YCSURF −40°C to +150°C Die Form

© 2004 Analog Devices, Inc. All rights reserved. Trademarks and regis­tered trademarks are the property of their respective owners.

PR04953–0–7/04(PrA)

Rev. PrA | Page 12 of 12