ANALOG DEVICES ADA4638-1 Service Manual

30 V Zero-Drift, Rail-to-Rail Output

–

A

Data Sheet

FEATURES

Single supply operation: 4.5 V to 30 V
Dual supply operation: ±2.25 V to ±15 V
Low offset voltage: 4 μV maximum
Input offset voltage drift: 0.05 μV/°C maximum
High gain: 130 dB minimum
High PSRR: 120 dB minimum
High CMRR: 130 dB minimum
Input common-mode range includes lower supply rail
Rail-to-rail output
Low supply current: 0.95 mA maximum

APPLICATIONS

Electronic weigh scale
Pressure and position sensors
Strain gage amplifiers
Medical instrumentation
Thermocouple amplifiers

Precision Amplifier

ADA4638-1

PIN CONFIGURATIONS

DA4638-1

1

NC

IN

2

TOP VIEW

(Not to Scale)

+IN

3

V–

4

NOTES

1. NC = NO CONNECT. DO NOT
CONNECT TO THI S PIN.

Figure 1. 8-Lead SOIC

ADA4638-1

1NC

2–IN

TOP VIEW

(Not to Scale)

3+IN

4V–

NOTES

1. NC = NO CONNECT. DO NOT CONNECT TO THI S PIN.

2. IT I S RECOMMENDE D THAT THE EXPOSED PAD BE
CONNECTED TO V–.

Figure 2. 8-Lead LFCSP

8

NC

V+

7

OUT

6

NC

5

8NC

7V+

6OUT

5NC

10072-001

10072-002

GENERAL DESCRIPTION

The ADA4638-1 is a high voltage, high precision, zero-drift
amplifier featuring rail-to-rail output swing. It is guaranteed to
operate from 4.5 V to 30 V single supply or ±2.25 V to ±15 V
dual supplies while consuming less than 0.95 mA of supply
current at ±5 V.

With an offset voltage of 4 µV, offset drift less than 0.05 µV/°C,
no 1/f noise, and input voltage noise of only 1.2 µV p-p (0.1 Hz
to 10 Hz), the ADA4638-1 is suited for high precision applications
where large error sources cannot be tolerated. Pressure sensors,
medical equipment, and strain gage amplifiers benefit greatly
from nearly zero drift over the wide operating temperature
range. Many applications can take advantage of the rail-to-rail
output swing provided by the ADA4638-1 to maximize the signal­to-noise ratio (SNR).

The ADA4638-1 is specified for the extended industrial (−40°C
to +125°C) temperature range and is available in 8-lead LFCSP
(3 mm × 3 mm) and SOIC packages.

Table 1. Analog Devices, Inc., Zero-Drift Op Amp Portfolio

Operating
Voltage Type Product

Offset
Voltage
(μV) Max

Offset
Voltage Drift
(μV/°C) Max

30 V Single ADA4638-1 4.5 0.08

Single AD8638 9 0.06 16 V
Dual AD8639 9 0.06

5 V

Single

ADA4528-1 2.5 0.015
AD8628 5 0.02
AD8538 13 0.1
ADA4051-1 15 0.1

Dual

AD8629 5 0.02
AD8539 13 0.1
ADA4051-2 15 0.1

Quad AD8630 5 0.02

Rev. 0

Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Anal og Devices for its use, nor for any infringements of patents or ot her
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] ©2011 Analog Devices, Inc. All rights reserved.

ADA4638-1 Data Sheet

TABLE OF CONTENTS

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

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

Pin Configurations ........................................................................... 1

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

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

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

Electrical Characteristics—30 V Operation ............................. 3

Electrical Characteristics—10 V Operation ............................. 4

Electrical Characteristics—5 V Operation................................ 5

Absolute Maximum Ratings............................................................ 6

Thermal Resistance ...................................................................... 6

ESD Caution.................................................................................. 6

REVISION HISTORY

10/11—Revision 0: Initial Version

Typical Performance Characteristics..............................................7

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

Differentiation ............................................................................ 16

Theory of Operation .................................................................. 17

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

No Output Phase Reversal ........................................................ 17

Noise Considerations................................................................. 18

Comparator Operation.............................................................. 18

Precision Low-Side Current Shunt Sensor.............................. 20

Printed Circuit Board Layout................................................... 20

Outline Dimensions....................................................................... 21

Ordering Guide .......................................................................... 21

Rev. 0 | Page 2 of 24

Data Sheet ADA4638-1

SPECIFICATIONS

ELECTRICAL CHARACTERISTICS—30 V OPERATION

VS = 30 V, VCM = VSY/2 V, TA = 25°C, unless otherwise specified.

Table 2.

Parameter Symbol Test Conditions/Comments Min Typ Max Unit

INPUT CHARACTERISTICS

Offset Voltage VOS 0.5 4.5 V

−40°C ≤ TA ≤ +125°C; SOIC 12.5 V

−40°C ≤ TA ≤ +125°C; LFCSP 14.5 V
Offset Voltage Drift ∆VOS/∆T −40°C ≤ TA ≤ +125°C; SOIC 0.08 V/°C

−40°C ≤ TA ≤ +125°C; LFCSP 0.1 V/°C
Input Bias Current IB 45 90 pA

−40°C ≤ TA ≤ +125°C 500 pA
Input Offset Current IOS 25 105 pA

−40°C ≤ TA ≤ +125°C 170 pA
Input Voltage Range 0 27 V
Common-Mode Rejection Ratio CMRR VCM = 0 V to 27 V 130 142 dB

−40°C ≤ TA ≤ +125°C 130 dB
Open-Loop Gain AVO R

−40°C ≤ TA ≤ +125°C 140 dB
Input Resistance, Common Mode R
Input Capacitance, Differential Mode C
Input Capacitance, Common Mode C

INCM

INDM

INCM

OUTPUT CHARACTERISTICS

Output Voltage High VOH R

−40°C ≤ TA ≤ +125°C 29.85 V
R

−40°C ≤ TA ≤ +125°C 29.35 V
Output Voltage Low VOL R

−40°C ≤ TA ≤ +125°C 95 mV
R

−40°C ≤ TA ≤ +125°C 445 mV
Short-Circuit Current ISC ±38 mA
Closed-Loop Output Impedance Z

f = 1 MHz, AV = +1 220 Ω

OUT

POWER SUPPLY

Power Supply Rejection Ratio PSRR VS = 4.5 V to 30 V 120 143 dB

−40°C ≤ TA ≤ +125°C 120 dB
Supply Current/Amplifier ISY I

−40°C ≤ TA ≤ +125°C 1.25 mA
DYNAMIC PERFORMANCE

Slew Rate SR RL = 10 kΩ, CL = 20 pF, AV = +1 1.5 V/s
Overload Recovery Time RL = 10 kΩ, CL = 20 pF, AV = −100 8 s
Settling Time to 0.1% tS V
Unity-Gain Crossover UGC VIN = 30 mV p-p, RL = 10 kΩ, CL = 20 pF, AV = +1
Phase Margin ΦM V
Gain-Bandwidth Product GBP VIN = 30 mV p-p, RL = 10 kΩ, CL = 20 pF, AV = +100 1.5 MHz

−3 dB Closed-Loop Bandwidth f

V

−3dB

NOISE PERFORMANCE

Voltage Noise en p-p f = 0.1 Hz to 10 Hz 1.2 µV p-p
Voltage Noise Density en f = 1 kHz 66 nV/√Hz
Current Noise Density in f = 1 kHz 0.1 pA/√Hz

= 10 kΩ, VO = 1 V to 29 V 140 165 dB

L

= 10 kΩ to VCM 29.90 29.92 V

L

= 2 kΩ to VCM 29.50 29.58 V

L

= 10 kΩ to VCM 50 60 mV

L

= 2 kΩ to VCM 235 270 mV

L

= 0 mA 0.85 1.05 mA

O

= 5 V step, RL = 10 kΩ, CL = 20 pF, AV = −1 4 µs

IN

= 30 mV p-p, RL = 10 kΩ, CL = 20 pF, AV = +1 69 Degrees

IN

= 30 mV p-p, RL = 10 kΩ, CL = 20 pF, AV = +1 2.5 MHz

IN

Rev. 0 | Page 3 of 24

330 GΩ
4 pF
9 pF

1.3

MHz

ADA4638-1 Data Sheet

ELECTRICAL CHARACTERISTICS—10 V OPERATION

VS = 10 V, VCM = VSY/2 V, TA = 25°C, unless otherwise specified.

Table 3.

Parameter Symbol Test Conditions/Comments Min Typ Max Unit

INPUT CHARACTERISTICS

Offset Voltage VOS 0.1 4 V

−40°C ≤ TA ≤ +125°C; SOIC 9 V

−40°C ≤ TA ≤ +125°C; LFCSP 12 V
Offset Voltage Drift ∆VOS/∆T −40°C ≤ TA ≤ +125°C; SOIC 0.05 V/°C

−40°C ≤ TA ≤ +125°C; LFCSP 0.08 V/°C
Input Bias Current IB 20 50 pA

−40°C ≤ TA ≤ +125°C 250 pA
Input Offset Current IOS 20 80 pA

−40°C ≤ TA ≤ +125°C 140 pA
Input Voltage Range 0 7 V
Common-Mode Rejection Ratio CMRR VCM = 0 V to 7 V 130 155 dB

−40°C ≤ TA ≤ +125°C 130 dB
Open-Loop Gain AVO R

−40°C ≤ TA ≤ +125°C 130 dB
Input Resistance, Common Mode R
Input Capacitance, Differential Mode C
Input Capacitance, Common Mode C

INCM

INDM

INCM

OUTPUT CHARACTERISTICS

Output Voltage High VOH R

−40°C ≤ TA ≤ +125°C 9.95 V
R

−40°C ≤ TA ≤ +125°C 9.75 V
Output Voltage Low VOL R

−40°C ≤ TA ≤ +125°C 40 mV
R

−40°C ≤ TA ≤ +125°C 145 mV
Short-Circuit Current ISC ±22 mA
Closed-Loop Output Impedance Z

f = 1 MHz, AV = +1 300 Ω

OUT

POWER SUPPLY

Power Supply Rejection Ratio PSRR VS = 4.5 V to 30 V 120 143 dB

−40°C ≤ TA ≤ +125°C 120 dB
Supply Current/Amplifier ISY I

−40°C ≤ TA ≤ +125°C 1.15 mA
DYNAMIC PERFORMANCE

Slew Rate SR RL = 10 kΩ, CL = 20 pF, AV = +1 1.5 V/s
Overload Recovery Time RL = 10 kΩ, CL = 20 pF, AV = −100 14 s
Settling Time to 0.1% tS V
Unity-Gain Crossover

UGC VIN = 30 mV p-p, RL = 10 kΩ, CL = 20 pF, AV = +1
Phase Margin ΦM V
Gain Bandwidth Product GBP VIN = 30 mV p-p, RL = 10 kΩ, CL = 20 pF, AV = +100 1.4 MHz

−3 dB Closed-Loop Bandwidth f

V

−3dB

NOISE PERFORMANCE

Voltage Noise en p-p f = 0.1 Hz to 10 Hz 1.2 µV p-p
Voltage Noise Density en f = 1 kHz 66 nV/√Hz
Current Noise Density in f = 1 kHz 0.1 pA/√Hz

= 10 kΩ, VO = 1 V to 9 V 130 160 dB

L

= 10 kΩ to VCM 9.96 9.97 V

L

= 2 kΩ to VCM 9.85 9.86 V

L

= 10 kΩ to VCM 20 25 mV

L

= 2 kΩ to VCM 80 90 mV

L

= 0 mA 0.8 0.95 mA

O

= 2 V step, RL = 10 kΩ, CL = 20 pF, AV = −1 3 µs

IN

= 30 mV p-p, RL = 10 kΩ, CL = 20 pF, AV = +1 67 Degrees

IN

= 30 mV p-p, RL = 10 kΩ, CL = 20 pF, AV = +1 1.9 MHz

IN

250 GΩ
4 pF
9 pF

1.1

MHz

Rev. 0 | Page 4 of 24

Data Sheet ADA4638-1

ELECTRICAL CHARACTERISTICS—5 V OPERATION

VS = 5 V, VCM = VSY/2 V, TA = 25°C, unless otherwise specified.

Table 4.

Parameter Symbol Test Conditions/Comments Min Typ Max Unit

INPUT CHARACTERISTICS

Offset Voltage VOS 1 13 V

−40°C ≤ TA ≤ +125°C; SOIC 18 V

−40°C ≤ TA ≤ +125°C; LFCSP 21 V
Offset Voltage Drift ∆VOS/∆T −40°C ≤ TA ≤ +125°C; SOIC 0.05 V/°C

−40°C ≤ TA ≤ +125°C; LFCSP 0.08 V/°C
Input Bias Current IB 30 90 pA

−40°C ≤ TA ≤ +125°C 230 pA
Input Offset Current IOS 60 170 pA

−40°C ≤ TA ≤ +125°C 200 pA
Input Voltage Range 0 3 V
Common-Mode Rejection Ratio CMRR VCM = 0 V to 3 V 118 140 dB

−40°C ≤ TA ≤ +125°C 118 dB
Open-Loop Gain AVO R

−40°C ≤ TA ≤ +125°C 125 dB
Input Resistance, Common Mode R
Input Capacitance, Differential Mode C
Input Capacitance, Common Mode C

INCM

INDM

INCM

OUTPUT CHARACTERISTICS

Output Voltage High VOH R

−40°C ≤ TA ≤ +125°C 4.97 V
R

−40°C ≤ TA ≤ +125°C 4.87 V
Output Voltage Low VOL R

−40°C ≤ TA ≤ +125°C 15 mV
R

−40°C ≤ TA ≤ +125°C 70 mV
Short-Circuit Current ISC ±22 mA
Closed-Loop Output Impedance Z

f = 1 MHz, AV = +1 340 Ω

OUT

POWER SUPPLY

Power Supply Rejection Ratio PSRR VS = 4.5 V to 30 V 120 143 dB

−40°C ≤ TA ≤ +125°C 120 dB
Supply Current/Amplifier ISY I

−40°C ≤ TA ≤ +125°C 1.15 mA
DYNAMIC PERFORMANCE

Slew Rate SR RL = 10 kΩ, CL = 20 pF, AV = +1 1.5 V/s
Overload Recovery Time RL = 10 kΩ, CL = 20 pF, AV = −100 22 s
Settling Time to 0.1% tS V
Unity-Gain Crossover UGC VIN = 20 mV p-p, RL = 10 kΩ, CL = 20 pF, AV = +1 1.0 MHz
Phase Margin ΦM V
Gain Bandwidth Product GBP VIN = 20 mV p-p, RL = 10 kΩ, CL = 20 pF, AV = +100 1.3 MHz

−3 dB Closed-Loop Bandwidth f

V

−3dB

NOISE PERFORMANCE

Voltage Noise en p-p f = 0.1 Hz to 10 Hz 1.2 µV p-p
Voltage Noise Density en f = 1 kHz 70 nV/√Hz
Current Noise Density in f = 1 kHz 0.015 pA/√Hz

= 10 kΩ, VO = 0.5 V to +4.5 V 125 150 dB

L

= 10 kΩ to VCM 4.98 4.984 V

L

= 2 kΩ to VCM 4.90 4.92 V

L

= 10 kΩ to VCM 7.5 10 mV

L

= 2 kΩ to VCM 37 45 mV

L

= 0 mA 0.8 0.95 mA

O

= 1 V step, RL = 10 kΩ, CL = 20 pF, AV = −1 3 µs

IN

= 20 mV p-p, RL = 10 kΩ, CL = 20 pF, AV = +1 64 Degrees

IN

= 20 mV p-p, RL = 10 kΩ, CL = 20 pF, AV = +1 1.8 MHz

IN

75 GΩ
4 pF
9 pF

Rev. 0 | Page 5 of 24

ADA4638-1 Data Sheet

ABSOLUTE MAXIMUM RATINGS

Table 5.

Parameter Rating

Supply Voltage 33 V
Input Voltage1 ±VSY
Input Current ±10 mA
Differential Input Voltage ±V
Output Short-Circuit Duration to GND Indefinite
Storage Temperature Range −65°C to +150°C
Operating Temperature Range −40°C to +125°C
Junction Temperature Range −65°C to +150°C
Lead Temperature (Soldering, 60 sec) 300°C

1

Input voltage should always be limited to less than 30 V.

SY

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

θJA is specified for a device soldered on a 4-layer JEDEC
standard board with zero airflow. For LFCSP packages, the
exposed pad is soldered to the board.

Table 6. Thermal Resistance

Package Type θJA θ

8-Lead SOIC 120 45 °C/W
8-Lead LFCSP 75 12 °C/W

Unit

JC

ESD CAUTION

Rev. 0 | Page 6 of 24

Data Sheet ADA4638-1

TYPICAL PERFORMANCE CHARACTERISTICS

TA = 25°C, unless otherwise noted.

12

10

VSY= ±2.5V
V

CM=VSY

150 UNITS

/2

30

25

VSY= ±15V
V

CM=VSY

150 UNITS

/2

8

6

4

NUMBER OF AMPLIF IERS

2

0

–9–8–7–6–5–4–3–2–1

–10

OFFSET VOLTAGE (µV)

012345678

Figure 3. Input Offset Voltage Distribution

20

18

16

14

12

10

8

6

NUMBER OF AMPLIFI ERS

4

2

0

0 0.010.020.030.040.050.060.070.08

TCVOS(µV/°C)

VSY= ±2.5V
V
–40°C < T
140 LFCSP UNITS

CM=VSY

/2

< +125°C

A

Figure 4. Input Offset Voltage Drift Distribution

20

15

10

NUMBER OF AMPLIFIERS

5

9

10

10072-003

0

–5.0

–4.5

–4.0

–3.5

–3.0

–2.5

–2.0

OFFSET VOLTAGE (µV)

0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

–1.5

–1.0

–0.5

5.0

10072-006

Figure 6. Input Offset Voltage Distribution

14

VSY= ±15V

/2

12

10

8

6

4

NUMBER OF AMPLIFIERS

2

0

0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08

10072-004

TCVOS(µV/°C)

V

CM=VSY

–40°C < T
140 LFCSP UNITS

< +125°C

A

10072-007

Figure 7. Input Offset Voltage Drift Distribution

30

25

20

15

10

NUMBER OF AMPLI FIERS

5

0

0 0.010.020.030.040.050.060.070.08

TCVOS (µV/°C)

VSY= ±2.5V
V

/2

CM=VSY

–40°C ≤ T
140 SOIC UNITS

≤ +125°C

A

Figure 5. Input Offset Voltage Drift Distribution

10072-105

Rev. 0 | Page 7 of 24

18

16

14

12

10

8

6

NUMBER OF AMPLI FIERS

4

2

0

0 0.010.020.030.040.050.060.070.08

TCVOS (µV/°C)

VSY=±15V

/2

V

CM=VSY

–40°C ≤ T
140 SOIC UNITS

≤ +125°C

A

Figure 8. Input Offset Voltage Drift Distribution

10072-108

ADA4638-1 Data Sheet

T

10

VSY= ±2.5V

8

6

4

2

AGE (µV)

0

–2

–4

OFFSET VOL

–6

–8

–10

0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0

COMMON-MODE VOLTAGE (V)

Figure 9. Input Offset Voltage vs. Common-Mode Voltage

10072-005

10

VSY=±15V

8

6

4

2

0

–2

–4

OFFSET VOLTAGE (µV)

–6

–8

–10

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

COMMON-MODE VOLTAGE (V)

Figure 12. Input Offset Voltage vs. Common-Mode Voltage

10072-008

200

150

100

50

0

–50

INPUT BIAS CURRENT (pA)

–100

–150

–50 –25 0 25 50 75 100 125

TEMPERATURE (°C)

I

IB+

–

B

V

SY

= ±2.5V

Figure 10. Input Bias Current vs. Temperature

150

VSY= ±2.5V

100

50

–

I

B

0

–50

INPUT BIAS CURRENT (pA)

–100

IB+

150

100

50

0

–50

–100

–150

INPUT BIAS CURRENT (pA)

–200

–250

–50 –25 0 25 50 75 100 125

10072-009

TEMPERATURE (°C)

IB+

–

I

B

V

SY

= ±15V

10072-012

Figure 13. Input Bias Current vs. Temperature

150

VSY=±15V

100

50

0

IB+

–50

INPUT BIAS CURRENT (pA)

–100

–

I

B

–150

0 0.5 1.0 1.5 2.0 2. 5 3.0

COMMON-MODE VOLTAGE (V)

Figure 11. Input Bias Current vs. Common-Mode Voltage

10072-010

–150

0 3 6 9 121518212427

COMMON-MODE VOLTAGE (V)

Figure 14. Input Bias Current vs. Common-Mode Voltage

10072-013

Rev. 0 | Page 8 of 24