ANALOG DEVICES AD623 Service Manual

Single-Supply, Rail-to-Rail, Low Cost

–

www.BDTIC.com/ADI

FEATURES

Easy to use
Higher performance than discrete design
Single-supply and dual-supply operation
Rail-to-rail output swing
Input voltage range extends 150 mV below

ground (single supply)
Low power, 550 μA maximum supply current
Gain set with one external resistor

Gain range: 1 (no resistor) to 1000
High accuracy dc performance

0.10% gain accuracy (G = 1)

0.35% gain accuracy (G > 1)

10 ppm maximum gain drift (G = 1)

200 μV maximum input offset voltage (AD623A)

2 μV/°C maximum input offset drift (AD623A)

100 μV maximum input offset voltage (AD623B)

1 μV/°C maximum input offset drift (AD623B)

25 nA maximum input bias current
Noise: 35 nV/√Hz RTI noise @ 1 kHz (G = 1)
Excellent ac specifications

90 dB minimum CMRR (G = 10); 70 dB minimum CMRR (G = 1)

at 60 Hz, 1 kΩ source imbalance
800 kHz bandwidth (G = 1)
20 μs settling time to 0.01% (G = 10)

APPLICATIONS

Low power medical instrumentation
Transducer interfaces
Thermocouple amplifiers
Industrial process controls
Difference amplifiers
Low power data acquisition

GENERAL DESCRIPTION

The AD623 is an integrated single-supply instrumentation
amplifier that delivers rail-to-rail output swing on a 3 V to 12 V
supply. The AD623 offers superior user flexibility by allowing
single gain set resistor programming and by conforming to the
8-lead industry standard pinout configuration. With no external
resistor, the AD623 is configured for unity gain (G = 1), and
with an external resistor, the AD623 can be programmed for
gains up to 1000.

Instrumentation Amplifier

AD623

CONNECTION DIAGRAM

AD623

1

R

G

2

–IN

3

+IN

4

–V

S

TOP VIEW

(Not to Scale)

Figure 1. 8-Lead PDIP (N), SOIC (R), and MSOP (RM) Packages

120

110

100

90

80

70

CMR (dB)

60

50

40

30

1 10 100 1k 10k 100k

Figure 2. CMR vs. Frequency, 5 V

The AD623 holds errors to a minimum by providing superior
ac CMRR that increases with increasing gain. Line noise, as
well as line harmonics, are rejected because the CMRR remains
constant up to 200 Hz. The AD623 has a wide input common­mode range and can amplify signals that have a common-mode
voltage 150 mV below ground. Although the design of the AD623
was optimized to operate from a single supply, the AD623 still
provides superior performance when operated from a dual
voltage supply (±2.5 V to ±6.0 V).

Low power consumption (1.5 mW at 3 V), wide supply voltage
range, and rail-to-rail output swing make the AD623 ideal
for battery-powered applications. The rail-to-rail output stage
maximizes the dynamic range when operating from low supply
voltages. The AD623 replaces discrete instrumentation amplifier
designs and offers superior linearity, temperature stability, and
reliability in a minimum of space.

8

+R

7

+V

6

OUTPUT

5

REF

FREQUENCY (Hz)

G

S

0778-001

×1000

×100

×10

×1

00778-002

, 0 VS

S

Rev. D

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: [phone] www.analog.com
Fax: [phone] ©1997–2008 Analog Devices, Inc. All rights reserved.

AD623

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TABLE OF CONTENTS

Features .............................................................................................. 1

Applications ....................................................................................... 1

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

Connection Diagram ....................................................................... 1

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

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

Single Supply ................................................................................. 3

Dual Supplies ................................................................................ 4

Both Dual and Single Supplies .................................................... 6

Absolute Maximum Ratings ............................................................ 7

ESD Caution .................................................................................. 7

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

Theory of Operation ...................................................................... 15

REVISION HISTORY

7/08—Rev. C to Rev. D

Updated Format .................................................................. Universal

Changes to Features Section and General Description Section . 1

Changes to Table 3 ............................................................................ 6

Changes to Figure 40 ...................................................................... 14

Changes to Theory of Operation Section .................................... 15

Changes to Figure 42 and Figure 43 ............................................. 16

Changes to Table 7 .......................................................................... 19

Updated Outline Dimensions ....................................................... 22

Changes to Ordering Guide .......................................................... 23

9/99—Rev. B to Rev. C

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

Basic Connection ....................................................................... 16

Gain Selection ............................................................................. 16

Reference Terminal .................................................................... 16

Input and Output Offset Voltage .............................................. 17

Input Protection ......................................................................... 17

RF Interference ........................................................................... 17

Grounding ................................................................................... 18

Input Differential and Common-Mode Range vs. Supply and

Gain .............................................................................................. 20

Outline Dimensions ....................................................................... 22

Ordering Guide .......................................................................... 23

Rev. D | Page 2 of 24

AD623

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SPECIFICATIONS

SINGLE SUPPLY

Typical @ 25°C single supply, VS = 5 V, and RL = 10 kΩ, unless otherwise noted.

Table 1.

AD623A AD623ARM AD623B
Parameter Conditions Min Typ Max Min Typ Max Min Typ Max Unit

GAIN

Gain Range 1 1000 1 1000 1 1000
Gain Error

Nonlinearity

G = 1 to 1000 50 50 50 ppm
Gain vs. Temperature

VOLTAGE OFFSET

Input Offset, V

Output Offset, V

Offset Referred to the

INPUT CURRENT

Input Bias Current 17 25 17 25 17 25 nA

Input Offset Current 0.25 2 0.25 2 0.25 2 nA

1

G = 1 0.03 0.10 0.03 0.10 0.03 0.05 %
G = 10 0.10 0.35 0.10 0.35 0.10 0.35 %
G = 100 0.10 0.35 0.10 0.35 0.10 0.35 %
G = 1000 0.10 0.35 0.10 0.35 0.10 0.35 %

G = 1 5 10 5 10 5 10 ppm/°C

1

G > 1

50 50 50 ppm/°C

25 200 200 500 25 100 μV

OSI

Over Temperature 350 650 160 μV
Average Tempco 0.1 2 0.1 2 0.1 1 μV/°C

200 1000 500 2000 200 500 μV

OSO

Over Temperature 1500 2600 1100 μV
Average Tempco 2.5 10 2.5 10 2.5 10 μV/°C

Input vs. Supply (PSR)
G = 1 80 100 80 100 80 100 dB
G = 10 100 120 100 120 100 120 dB
G = 100 120 140 120 140 120 140 dB
G = 1000 120 140 120 140 120 140 dB

Over Temperature 27.5 27.5 27.5 nA
Average Tempco 25 25 25 pA/°C

Over Temperature 2.5 2.5 2.5 nA
Average Tempco 5 5 5 pA/°C

G =
1 + (100 k/R

G1 V

=

OUT

0.05 V to 3.5 V
G > 1 V

0.05 V to 4.5 V

G1 V

0.05 V to 3.5 V
G > 1 V

0.05 V to 4.5 V

Total RTI error =
V

=

OUT

=

OUT

=

OUT

+ V

/G

OSI

OSO

)

G

Rev. D | Page 3 of 24

AD623

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AD623A AD623ARM AD623B
Parameter Conditions Min Typ Max Min Typ Max Min Typ Max Unit

INPUT

Input Impedance

Differential 2||2 2||2 2||2 GΩ||pF
Common-Mode 2||2 2||2 2||2 GΩ||pF

Input Voltage Range

Common-Mode Rejection

at 60 Hz with 1 kΩ Source

Imbalance
G = 1 VCM = 0 V to 3 V 70 80 70 80 77 86 dB
G = 10 VCM = 0 V to 3 V 90 100 90 100 94 100 dB
G = 100 VCM = 0 V to 3 V 105 110 105 110 105 110 dB
G = 1000 VCM = 0 V to 3 V 105 110 105 110 105 110 dB

OUTPUT

Output Swing RL = 10 kΩ 0.01

R

DYNAMIC RESPONSE

Small Signal −3 dB Bandwidth

G = 1 800 800 800 kHz
G = 10 100 100 100 kHz
G = 100 10 10 10 kHz
G = 1000 2 2 2 kHz

Slew Rate 0.3 0.3 0.3 V/μs
Settling Time to 0.01% VS = 5 V

G = 1 Step size: 3.5 V 30 30 30 μs
G = 10

1

Does not include effects of external resistor, RG.

2

One input grounded. G = 1.

2

VS = 3 V to 12 V

(−V

0.15

) −

S

(+V

1.5

) −

(−VS) −

S

0.15

(+V

1.5

) −

(−VS) −

S

0.15

(+V

V

) −

S

1.5

= 100 kΩ 0.01

L

Step size: 4 V,

= 1.8 V

V

CM

20 20 20 μs

(+V

0.5
(+V

0.15

0.01

) −

S

0.01

) −

S

(+V

0.5
(+VS) −

0.15

0.01

) −

S

0.01

) −

(+V

S

0.5
(+VS) −

0.15

V

V

DUAL SUPPLIES

Typical @ 25°C dual supply, VS = ±5 V, and RL = 10 kΩ, unless otherwise noted.

Table 2.

AD623A AD623ARM AD623B
Parameter Conditions Min Typ Max Min Typ Max Min Typ Max Unit

GAIN

G =
1 + (100 k/R

)

G

Gain Range 1 1000 1 1000 1 1000
Gain Error

1

G1 V

OUT

=

−4.8 V to +3.5 V
G > 1 V

OUT

=

0.05 V to 4.5 V
G = 1 0.03 0.10 0.03 0.10 0.03 0.05 %
G = 10 0.10 0.35 0.10 0.35 0.10 0.35 %
G = 100 0.10 0.35 0.10 0.35 0.10 0.35 %
G = 1000 0.10 0.35 0.10 0.35 0.10 0.35 %

Rev. D | Page 4 of 24

AD623

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AD623A AD623ARM AD623B
Parameter Conditions Min Typ Max Min Typ Max Min Typ Max Unit

Nonlinearity

G1 V

OUT

=

−4.8 V to +3.5 V
G > 1 V

OUT

=

−4.8 V to +4.5 V
G = 1 to 1000 50 50 50 ppm
Gain vs. Temperature

G = 1 5 10 5 10 5 10 ppm/°C

1

G > 1

50 50 50 ppm/°C

VOLTAGE OFFSET

Input Offset, V

25 200 200 500 25 100 μV

OSI

Total RTI error =

+ V

V

/G

OSI

OSO

Over Temperature 350 650 160 μV
Average Tempco 0.1 2 0.1 2 0.1 1 μV/°C

Output Offset, V

200 1000 500 2000 200 500 μV

OSO

Over Temperature 1500 2600 1100 μV
Average Tempco 2.5 10 2.5 10 2.5 10 μV/°C

Offset Referred to the Input

vs. Supply (PSR)
G = 1 80 100 80 100 80 100 dB
G = 10 100 120 100 120 100 120 dB
G = 100 120 140 120 140 120 140 dB
G = 1000 120 140 120 140 120 140 dB

INPUT CURRENT

Input Bias Current 17 25 17 25 17 25 nA

Over Temperature 27.5 27.5 27.5 nA
Average Tempco 25 25 25 pA/°C

Input Offset Current 0.25 2 0.25 2 0.25 2 nA

Over Temperature 2.5 2.5 2.5 nA
Average Tempco 5 5 5 pA/°C

INPUT

Input Impedance

Differential 2||2 2||2 2||2 GΩ||pF
Common-Mode 2||2 2||2 2||2 GΩ||pF

Input Voltage Range

2

VS = +2.5 V to
±6 V

Common-Mode Rejection at

60 Hz with 1 kΩ Source

Imbalance
G = 1

= +3.5 V to

V

CM

−5.15 V

G = 10

= +3.5 V to

V

CM

−5.15 V

G = 100

= +3.5 V to

V

CM

−5.15 V

G = 1000

= +3.5 V to

V

CM

−5.15 V

OUTPUT

Output Swing

R

= 10 kΩ,

R

L

= ±5 V

V

S

= 100 kΩ

L

(−VS) –

0.15

(+VS) –

1.5

(−VS) –

0.15

(+VS) –

1.5

(−VS) –

0.15

(+VS) –

V

1.5

70 80 70 80 77 86 dB

90 100 90 100 94 100 dB

105 110 105 110 105 110 dB

105 110 105 110 105 110 dB

(−V

0.2
(−V

0.05

) +

S

) +

S

(+V

0.5
(+V

0.15

) −

(−VS) +

S

0.2

) −

(−VS) +

S

0.05

(+V

0.5
(+V

0.15

S

S

) −

) −

(−VS) +

0.2
(−VS) +

0.05

(+V

V

) −

S

0.5
(+V

V

) −

S

0.15

Rev. D | Page 5 of 24

AD623

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AD623A AD623ARM AD623B
Parameter Conditions Min Typ Max Min Typ Max Min Typ Max Unit

DYNAMIC RESPONSE

Small Signal −3 dB Bandwidth

G = 1 800 800 800 kHz
G = 10 100 100 100 kHz
G = 100 10 10 10 kHz

G = 1000 2 2 2 kHz
Slew Rate 0.3 0.3 0.3 V/μs
Settling Time to 0.01%

G = 1 30 30 30 μs

G = 10 20 20 20 μs

1

Does not include effects of external resistor, RG.

2

One input grounded. G = 1.

= ±5 V,

V

S

5 V step

BOTH DUAL AND SINGLE SUPPLIES

Table 3.

AD623A AD623ARM AD623B
Parameter Conditions Min Typ Max Min Typ Max Min Typ Max Unit

NOISE

Voltage Noise, 1 kHz

Input, Voltage Noise, eni 35 35 35 nV/√Hz

Output, Voltage Noise, eno 50 50 50 nV/√Hz
RTI, 0.1 Hz to 10 Hz

G = 1 3.0 3.0 3.0 μV p-p

G = 1000 1.5 1.5 1.5 μV p-p
Current Noise f = 1 kHz 100 100 100 fA/√Hz

0.1 Hz to 10 Hz 1.5 1.5 1.5 pA p-p

REFERENCE INPUT

RIN

IIN VIN+, V
Voltage Range −VS +VS −VS +VS −VS +VS V
Gain to Output

POWER SUPPLY

Operating Range Dual supply ±2.5 ±6 ±2.5 ±6 ±2.5 ±6 V
Single supply 2.7 12 2.7 12 2.7 12 V
Quiescent Current Dual supply 375 550 375 550 375 550 μA
Single supply 305 480 305 480 305 480 μA
Over Temperature 625 625 625 μA

TEMPERATURE RANGE

For Specified Performance −40 +85 −40 +85 −40 +85 °C

Tot al RT I nois e =

2

()

()

+

no

ni

= 0 V 50 60 50 60 50 60 μA

REF

2

/Gee

100 ±
20%

1 ±

0.0002

100 ±
20%

1 ±

0.0002

100 ±
20%

1 ±

0.0002

kΩ

V

Rev. D | Page 6 of 24

AD623

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ABSOLUTE MAXIMUM RATINGS

Table 4.

Parameter Rating

Supply Voltage ±6 V

Internal Power Dissipation

Differential Input Voltage ±6 V

Output Short-Circuit Duration Indefinite

Storage Temperature Range −65°C to +125°C

Operating Temperature Range −40°C to +85°C

Lead Temperature (Soldering, 10 sec) 300°C

1

Specification is for device in free air:

8-Lead PDIP Package: θJA = 95°C/W

8-Lead SOIC Package: θ

8-Lead MSOP Package: θ

1

650 mW

= 155°C/W

JA

= 200°C/W.

JA

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.

ESD CAUTION

Rev. D | Page 7 of 24

AD623

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TYPICAL PERFORMANCE CHARACTERISTICS

At 25°C, VS = ±5 V, and RL = 10 kΩ, unless otherwise noted.

300

280

260

240

220

200

180

160

140

UNITS

120

100

80

60

40

20

0

–100 –80 –60 –40 –20 0 20 40 60 80 100 120 140

INPUT OFFSET VOLTAGE (µV)

00778-003

Figure 3. Typical Distribution of Input Of fset V oltage; Packa ge Option N-8, R-8

480

22

20

18

16

14

12

UNITS

10

8

6

4

2

0

–600 –500 –400 –300 –200 –100 0 100 200 300 400 500

OUTPUT OFFSET VOLTAGE (µV)

Figure 6. Typical Distribution of Output Offset Voltage, V

Single Supply, V

210

= −0.125 V; Package Option N-8, R-8

REF

= 5 V,

S

00778-006

420

360

300

240

UNITS

180

120

60

0

–800 –600 –400 –200 0 200 400 600 800

OUTPUT OFFSET VOLTAGE (µV)

00778-004

Figure 4. Typical D istribution of Output Offset Voltage; Package Opt ion N-8, R-8

22

20

18

16

14

12

UNITS

10

8

6

4

2

0

–80 –60 –40 –20 0 20 40 60 80 100

INPUT OFFSET VOLTAGE (µV)

00778-005

Figure 5. Typical Distribution of Input Offset Voltage, VS = 5 V,

Single Supply, V

= −0.125 V; Package Option N-8, R-8

REF

180

150

120

UNITS

90

60

30

0

–0.245 –0.240 –0. 235 –0.230 –0.225 –0. 220 –0. 215 –0. 210

INPUT OFF SET CURRENT (n A)

00778-007

Figure 7. Typical Distribution for Input Offset Current; Package Option N-8, R-8

20

18

16

14

12

10

UNITS

8

6

4

2

0

–0.025 –0.020 –0.015 –0.010 –0.005 0 0.005 0.010

INPUT OFF SET CURRENT (n A)

00778-008

Figure 8. Typical Distribution for Input Offset Current, VS = 5 V,

Single Supply, V

= −0.125 V; Package Option N-8, R-8

REF

Rev. D | Page 8 of 24