ANALOG DEVICES AD8276, AD8277 Service Manual

Low Power, Wide Supply Range, Low Cost

FEATURES

Wide input range beyond supplies
Rugged input overvoltage protection
Low supply current: 200 μA maximum per channel
Low power dissipation: 0.5 mW at V
Bandwidth: 550 kHz
CMRR: 86 dB minimum, dc to 10 kHz
Low offset voltage drift: ±2 μV/°C maximum (B Grade)
Low gain drift: 1 ppm/°C maximum (B Grade)
Enhanced slew rate: 1.1 V/μs
Wide power supply range:

Single supply: 2 V to 36 V
Dual supplies: ±2 V to ±18 V

APPLICATIONS

Voltage measurement and monitoring
Current measurement and monitoring
Differential output instrumentation amplifier
Portable, battery-powered equipment
Test and measurement

GENERAL DESCRIPTION

The AD8276/AD8277 are general-purpose, unity-gain difference
amplifiers intended for precision signal conditioning in power
critical applications that require both high performance and low
power. They provide exceptional common-mode rejection ratio
(86 dB) and high bandwidth while amplifying signals well beyond
the supply rails. The on-chip resistors are laser-trimmed for
excellent gain accuracy and high CMRR. They also have extremely
low gain drift vs. temperature.

The common-mode range of the amplifiers extends to almost
double the supply voltage, making these amplifiers ideal for single­supply applications that require a high common-mode voltage
range. The internal resistors and ESD circuitry at the inputs also
provide overvoltage protection to the op amps.

The AD8276/AD8277 are unity-gain stable. While they are
optimized for use as difference amplifiers, they can also be
connected in high precision, single-ended configurations with
G = −1, +1, +2. The AD8276/AD8277 provide an integrated
precision solution that has smaller size, lower cost, and better
performance than a discrete alternative.

The AD8276/AD8277 operate on single supplies (2.0 V to 36 V)
or dual supplies (±2 V to ±18 V). The maximum quiescent
supply current is 200 A per channel, which is ideal for battery­operated and portable systems.

= 2.5 V

S

Unity-Gain Difference Amplifiers

AD8276/AD8277

FUNCTIONAL BLOCK DIAGRAM

+VS

7

40kΩ 40kΩ

2

–IN

40kΩ

3 1

+IN

Figure 1. AD8276

40kΩ 40kΩ

2

–INA

40kΩ

3 14

+INA

40kΩ 40kΩ

6

–INB

40kΩ

5 8

+INB

Figure 2. AD8277

Table 1. Difference Amplifiers by Category

Low
Distortion

High
Voltage

AD8270 AD628 AD8202 (U) AD8276
AD8271 AD629 AD8203 (U) AD8277
AD8273 AD8205 (B) AD8278
AD8274 AD8206 (B)
AMP03 AD8216 (B)

1

U = unidirectional, B = bidirectional.

The AD8276 is available in the space-saving 8-lead MSOP and
SOIC packages, and the AD8277 is offered in a 14-lead SOIC
package. Both are specified for performance over the industrial
temperature range of −40°C to +85°C and are fully RoHS
compliant.

AD8276

4

–VS

+VS

11

AD8277

4

–VS

Current
Sensing

5

SENSE

6

OUT

40kΩ

40kΩ

40kΩ

REF

07692-001

12

SENSEA

13

OUTA

REFA

10

SENSEB

9

OUTB

REFB

07692-052

1

Low Power

Rev. B

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rights of third parties that may result from its use. Specifications subject to change without notice. No
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One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: [phone] www.analog.com
Fax: [phone] ©2009–2010 Analog Devices, Inc. All rights reserved.

AD8276/AD8277

TABLE OF CONTENTS

Features .............................................................................................. 1

Applications ....................................................................................... 1 

General Description ......................................................................... 1

Functional Block Diagram .............................................................. 1

Revision History ............................................................................... 2

Specifications ..................................................................................... 3

Absolute Maximum Ratings ............................................................ 5

Thermal Resistance ...................................................................... 5

Maximum Power Dissipation ..................................................... 5

Short-Circuit Current .................................................................. 5

ESD Caution .................................................................................. 5

Pin Configurations and Function Descriptions ........................... 6

Typical Performance Characteristics ............................................. 8

Theory of Operation ...................................................................... 14

Circuit Information .................................................................... 14

Driving the AD8276/AD8277 .................................................. 14

Input Voltage Range ................................................................... 14

Power Supplies ............................................................................ 15

Applications Information .............................................................. 16

Configurations ............................................................................ 16 

Differential Output .................................................................... 16

Current Source ............................................................................ 17

Voltage and Current Monitoring .............................................. 17

Instrumentation Amplifier........................................................ 18

RTD .............................................................................................. 18 

Outline Dimensions ....................................................................... 19

Ordering Guide .......................................................................... 20

REVISION HISTORY

4/10—Rev. A to Rev. B

Changes to Figure 53 ...................................................................... 18

Updated Outline Dimensions ....................................................... 19

7/09—Rev. 0 to Rev. A

Added AD8277 ................................................................... Universal

Changes to Features Section............................................................ 1

Changes to General Description Section ...................................... 1

Added Figure 2; Renumbered Sequentially .................................. 1

Changes to Specifications Section .................................................. 3

Changes to Figure 3 and Table 5 ..................................................... 5

Added Figure 5 and Table 7; Renumbered Sequentially ............. 7

Changes to Figure 10 ........................................................................ 8

Changes to Figure 34 ...................................................................... 12

Added Figure 36 ............................................................................. 13

Changes to Input Voltage Range Section .................................... 14

Changes to Power Supplies Section and Added Figure 40 ........ 15

Added to Figure 40 ......................................................................... 15

Changes to Differential Output Section ...................................... 16

Added Figure 47 and Changes to Current Source Section ....... 17

Added Voltage and Current Monitoring Section and Figure 49..... 17

Moved Instrumentation Amplifier Section and Added RTD

Section ........................................................................................................ 18

Changes to Ordering Guide .......................................................... 20

5/09—Revision 0: Initial Version

Rev. B | Page 2 of 20

AD8276/AD8277

SPECIFICATIONS

VS = ±5 V to ±15 V, V
otherwise noted.

Table 2.

G = 1
Grade B Grade A
Parameter Conditions Min Typ Max Min Typ Max Unit

INPUT CHARACTERISTICS

System Offset1 100 200 100 500 µV

vs. Temperature TA = −40°C to +85°C 200 500 µV
Average Temperature

Coefficient

vs. Power Supply VS = ±5 V to ±18 V 5 10 µV/V

Common-Mode Rejection

Ratio (RTI)
Input Voltage Range2 −2(VS + 0.1) +2(VS − 1.5) −2(VS + 0.1) +2(VS − 1.5) V
Impedance3

Differential 80 80 kΩ

Common Mode 40 40 kΩ

DYNAMIC PERFORMANCE

Bandwidth 550 550 kHz
Slew Rate 0.9 1.1 0.9 1.1 V/µs
Settling Time to 0.01%

Settling Time to 0.001% 16 16 µs
Channel Separation f = 1 kHz 130 130 dB

GAIN

Gain Error 0.005 0.02 0.01 0.05 %
Gain Drift TA = −40°C to +85°C 1 5 ppm/°C
Gain Nonlinearity V

OUTPUT CHARACTERISTICS

Output Voltage Swing4

Short-Circuit Current Limit ±15 ±15 mA
Capacitive Load Drive 200 200 pF

NOISE5

Output Voltage Noise f = 0.1 Hz to 10 Hz 2 2 V p-p
f = 1 kHz 65 70 65 70 nV/√Hz

POWER SUPPLY

Supply Current6 200 200 A

vs. Temperature TA = −40°C to +85°C 250 250 A
Operating Voltage Range7 ±2 ±18 ±2 ±18 V

TEMPERATURE RANGE

Operating Range −40 +125 −40 +125 °C

1

Includes input bias and offset current errors, RTO (referred to output).

2

The input voltage range may also be limited by absolute maximum input voltage or by the output swing. See the section in the The

Operation

3

Internal resistors are trimmed to be ratio matched and have ±20% absolute accuracy.

4

Output voltage swing varies with supply voltage and temperature. See Figur through for details. e 18 Figure 21

5

Includes amplifier voltage and current noise, as well as noise from internal resistors.

6

Supply current varies with supply voltage and temperature. See Figure and for details. 22 Figure 24

7

Unbalanced dual supplies can be used, such as −VS = −0.5 V and +VS = +2 V. The positive supply rail must be at least 2 V above the negative supply and reference

voltage.

section for details.

= 0 V, TA = 25°C, RL = 10 k connected to ground, G = 1 difference amplifier configuration, unless

REF

T

= −40°C to +85°C 0.5 2 2 5 µV/°C

A

VS = ±15 V, VCM = ±27 V,

= 0 Ω 86 80 dB

R

S

10 V step on output,

= 100 pF

C

L

= 20 V p-p 5 10 ppm

OUT

= ±15 V, RL = 10 kΩ,

V

S

= −40°C to +85°C −VS + 0.2 +VS − 0.2 −VS + 0.2 +VS − 0.2 V

T

A

15 15 µs

Input Voltage Range ory of

Rev. B | Page 3 of 20

AD8276/AD8277

VS = +2.7 V to <±5 V, V
otherwise noted.

Table 3.

G = 1
Grade B Grade A
Parameter Conditions Min Typ Max Min Typ Max Unit

INPUT CHARACTERISTICS

System Offset1 100 200 100 500 µV

vs. Temperature TA = −40°C to +85°C 200 500 µV
Average Temperature

Coefficient

vs. Power Supply VS = ±5 V to ±18 V 5 10 µV/V

Common-Mode Rejection

Ratio (RTI)

Input Voltage Range2 −2(VS + 0.1) +2( VS − 1.5) −2(VS + 0.1) +2(VS − 1.5) V
Impedance3

Differential 80 80 kΩ
Common Mode 40 40 kΩ

DYNAMIC PERFORMANCE

Bandwidth 450 450 kHz
Slew Rate 1.0 1.0 V/µs
Settling Time to 0.01%

Channel Separation f = 1 kHz 130 130 dB

GAIN

Gain Error 0.005 0.02 0.01 0.05 %
Gain Drift TA = −40°C to +85°C 1 5 ppm/°C

OUTPUT CHARACTERISTICS

Output Swing4

Short-Circuit Current

Limit

Capacitive Load Drive 200 200 pF

NOISE5

Output Voltage Noise f = 0.1 Hz to 10 Hz 2 2 V p-p
f = 1 kHz 65 65 nV/√Hz

POWER SUPPLY

Supply Current6 T
Operating Voltage

Range

TEMPERATURE RANGE

Operating Range −40 +125 −40 +125 °C

1

Includes input bias and offset current errors, RTO (referred to output).

2

The input voltage range may also be limited by absolute maximum input voltage or by the output swing. See the section in the

section for details.

3

Internal resistors are trimmed to be ratio matched and have ±20% absolute accuracy.

4

Output voltage swing varies with supply voltage and temperature. See Figur through for details. e 18 Figure 21

5

Includes amplifier voltage and current noise, as well as noise from internal resistors.

6

Supply current varies with supply voltage and temperature. See Figure and for details. 23 Figure 24

= midsupply, TA = 25°C, RL = 10 k connected to midsupply, G = 1 difference amplifier configuration, unless

REF

= −40°C to +85°C 0.5 2 2 5 µV/°C

T

A

VS = 2.7 V, VCM = 0 V
to 2.4 V, R

= ±5 V, VCM = −10 V

V

S

to +7 V, R

= 0 Ω

S

= 0 Ω 86 80 dB

S

8 V step on output,

= 100 pF, VS = 10 V

C

L

= 10 kΩ ,

R

L

= −40°C to +85°C −VS + 0.1 +VS − 0.15 −VS + 0.1 +VS − 0.15 V

T

A

86 80 dB

5 5 µs

±10 ±10 mA

= −40°C to +85°C 200 200 A

A

2.0 36 2.0 36 V

Input Voltage Range Theory of Operation

Rev. B | Page 4 of 20

AD8276/AD8277

ABSOLUTE MAXIMUM RATINGS

2.0

Table 4.

Parameter Rating

Supply Voltage ±18 V
Maximum Voltage at Any Input Pin −VS + 40 V
Minimum Voltage at Any Input Pin +VS − 40 V
Storage Temperature Range −65°C to +150°C
Specified Temperature Range −40°C to +85°C
Package Glass Transition Temperature (TG) 150°C

Stresses above those listed under Absolute Maximum Ratings
may cause permanent damage to the device. This is a stress
rating only; 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.

THERMAL RESISTANCE

The θJA values in Tabl e 5 assume a 4-layer JEDEC standard
board with zero airflow.

Table 5.

Package Type θJA Unit

8-Lead MSOP 135 °C/W
8-Lead SOIC 121 °C/W
14-Lead SOIC 105 °C/W

MAXIMUM POWER DISSIPATION

The maximum safe power dissipation for the AD8276/AD8277
is limited by the associated rise in junction temperature (T
the die. At approximately 150°C, which is the glass transition
temperature, the properties of the plastic change. Even temporarily
exceeding this temperature limit may change the stresses that the
package exerts on the die, permanently shifting the parametric
performance of the amplifiers. Exceeding a temperature of 150°C
for an extended period may result in a loss of functionality.

) on

J

1.6

1.2

0.8

0.4

MAXIMUM POWER DISSIPATI O N (W )

0

–50 0–25 25 50 75 100 125

Figure 3. Maximum Power Dissipation vs. Ambient Temperature

SHORT-CIRCUIT CURRENT

The AD8276/AD8277 have built-in, short-circuit protection
that limits the output current (see Figure 25 for more information).
While the short-circuit condition itself does not damage the
part, the heat generated by the condition can cause the part to
exceed its maximum junction temperature, with corresponding
negative effects on reliability. Figure 3 and Figure 25, combined
with knowledge of the supply voltages and ambient temperature of
the part, can be used to determine whether a short circuit will
cause the part to exceed its maximum junction temperature.

ESD CAUTION

14-LEAD SO IC

θ

= 105°C/W

JA

8-LEAD MSO P

θ

= 135°C/W

JA

AMBIENT TEMERATURE (°C)

TJ MAX = 150°C

8-LEAD SOIC

θ

= 121°C/W

JA

07692-002

Rev. B | Page 5 of 20

AD8276/AD8277

PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS

REF

1

AD8276

2

–IN

TOP VIEW

+IN

3

(Not to S cale)

–VS

4

NC = NO CONNECT

Figure 4. AD8276 8-Lead MSOP Pin Configuration

Table 6. AD8276 Pin Function Descriptions

Pin No. Mnemonic Description

1 REF Reference Voltage Input.
2 −IN Inverting Input.
3 +IN Noninverting Input.
4 −VS Negative Supply.
5 SENSE Sense Terminal.
6 OUT Output.
7 +VS Positive Supply.
8 NC No Connect.

8
7
6
5

NC
+VS
OUT
SENSE

REF

1

AD8276

–IN

2

TOP VIEW

+IN

3

(Not to Scale)

4

–VS

7692-003

NC = NO CONNECT

8
7
6
5

NC
+VS
OUT
SENSE

7692-004

Figure 5. AD8276 8-Lead SOIC Pin Configuration

Rev. B | Page 6 of 20