Analog Devices AD8538 Service Manual

Low Power, Precision Auto-Zero Op Amp

AD8538

FEATURES PIN CONFIGURATION DIAGRAMS

Low offset voltage: 13 µV maximum
Input offset drift: 0.03 µV/°C
Single-supply operation: 2.7 V to 5.5 V
High gain, CMRR, and PSRR
Low input bias current: 25 pA
Low supply current: 180 µA

OUT

V–

+IN

1

AD8538

2

TOP VIEW

(Not to Scale)

3

V+

5

–IN

4

Figure 1. 5-Lead TSOT-23 (UJ-5)

05624-002

APPLICATIONS

NC

Mobile communications
Portable instrumentation
Battery-powered devices
Sensor interfaces
Temperature measurement
Electronic scales

GENERAL DESCRIPTION

The AD8538 is a very high precision amplifier featuring
extremely low offset voltage, low input bias current, and low
power consumption. The supply current is less than 180 μA at

5.0 V. Operation is fully specified from 2.7 V to 5.0 V single
supply (±1.35 V to ±2.5 V dual supply).

The AD8538 operates using very low power making this
amplifier ideal for battery-powered devices and portable
equipment.

The AD8538 is specified over the extended industrial temperature
range (−40°C to +125°C). The AD8538 amplifier is available in
5-lead TSOT-23, and 8-lead, narrow body SOIC packages.

1

AD8538

2

−IN

3

+IN

TOP VIEW

(Not to Scale)

4

V−

NC = NO CO NNECT

Figure 2. 8-Lead SOIC_N (R-8)

NC

8

7

V+

6

OUT

5

NC

05624-001

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.

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Tel: [phone]
Fax: [phone] © 2005 Analog Devices, Inc. All rights reserved.

www.analog.com

AD8538

TABLE OF CONTENTS

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

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

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

Pin Configuration Diagrams........................................................... 1

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

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

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

Electrical Specifications............................................................... 3

REVISION HISTORY

10/05—Revision 0: Initial Version

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

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

Typical Perf or m an c e Charac t e r istic s ..............................................6

Outline Dimensions ....................................................................... 12

Ordering Guide .......................................................................... 12

Rev. 0 | Page 2 of 12

AD8538

SPECIFICATIONS

ELECTRICAL SPECIFICATIONS

@VS = 5.0 V, VCM = 2.5 V, VO = 2.5 V, TA = 25°C, unless otherwise specified.

Table 1.

Parameter Symbol Conditions Min Typ Max Unit

INPUT CHARACTERISTICS

Offset Voltage V

OS

−40°C ≤ TA ≤ +125°C 30 µV
Input Bias Current I

B

−40°C ≤ TA ≤ +85°C 35 100 pA

−40°C ≤ TA ≤ +125°C 0.7 1.0 nA
Input Offset Current I

OS

−40°C ≤ TA ≤ +125°C 150 pA
Input Voltage Range 0 5 V

Common-Mode Rejection Ratio CMRR VCM = 0 V to 5 V 115 150 dB

−40°C ≤ TA ≤ +125°C; VCM = 0.2 V to 4.8 V 100 135 dB
Large Signal Voltage Gain A

VO

−40°C ≤ TA ≤ +125°C 110 135 dB
Offset Voltage Drift

ΔV

OS

OUTPUT CHARACTERISTICS

Output Voltage High V

OH

−40°C ≤ TA ≤ +125°C 4.98 V
R

−40°C ≤ TA ≤ +125°C 4.94 V
Output Voltage Low V

OL

−40°C ≤ TA ≤ +125°C 2.8 7 mV
R

−40°C ≤ TA ≤ +125°C 20 30 mV
Short-Circuit Limit I

SC

POWER SUPPLY

Power Supply Rejection Ratio PSRR VS = 2.7 V to 5.0 V 105 125 dB

−40°C ≤ TA ≤ +125°C 100 125 dB
Supply Current/Amplifier I

SY

−40°C ≤ TA ≤ +125°C 190 215 µA
DYNAMIC PERFORMANCE

Slew Rate SR RL =10 kΩ 0.4 V/µs
Settling Time 0.01% t

S

Overload Recovery Time 0.05 ms
Gain Bandwidth Product GBP 600 kHz
Phase Margin Ø

O

NOISE PERFORMANCE

Voltage Noise e
Voltage Noise Density e

n p-p

n

5 13 µV

15 25 pA

20 50 pA

RL = 10 kΩ, VO = 0.1 V to 4.9 V 115 141 dB

/ΔT

−40°C ≤ T

≤ +125°C 0.03 0.1 µV/°C

A

RL = 100 kΩ to ground 4.99 4.998 V

= 10 kΩ to ground 4.95 4.970 V

L

RL = 100 kΩ to V+ 1.9 5 mV

= 10 kΩ to V+ 17 20 mV

L

±25 mA

IO = 0 150 180 µA

G = ±1, 2 V step, CL = 20 pF, RL = 1 kΩ 10 s

RL = 10 kΩ, RL = 100 kΩ, CL = 20 pF 65 Degrees

f = 0.1 Hz to 10 Hz 2.0 µV p-p
f = 1 kHz 50

nV/√Hz

Rev. 0 | Page 3 of 12

AD8538

@ VS = 2.7 V, VCM = 1.35 V, VO = 1.35 V, TA = 25°C, unless otherwise specified.

Table 2.

Parameter Symbol Conditions Min Typ Max Unit

INPUT CHARACTERISTICS

Offset Voltage V

OS

−40°C ≤ TA ≤ +125°C 30 µV
Input Bias Current I

B

−40°C ≤ TA ≤ +85°C 35 100 pA

−40°C ≤ TA ≤ +125°C 0.7 1.0 nA
Input Offset Current I

OS

−40°C ≤ TA ≤ +125°C 150 pA
Input Voltage Range 0 2.7 V
Common-Mode Rejection Ratio CMRR VCM = 0 V to 2.5 V 110 140 dB

−40°C ≤ TA ≤ +125°C 100 135 dB
Large Signal Voltage Gain A

VO

−40°C ≤ TA ≤ +125°C 105 135 dB
Offset Voltage Drift

ΔV

OS

OUTPUT CHARACTERISTICS

Output Voltage High V

OH

−40°C ≤ TA ≤ +125°C 2.68 V
R

−40°C ≤ TA ≤ +125°C 2.66 V
Output Voltage Low V

OL

−40°C ≤ TA ≤ +125°C 2.4 5 mV
R

−40°C ≤ TA ≤ +125°C 20 25 mV
Short-Circuit Limit I

SC

POWER SUPPLY

Power Supply Rejection Ratio PSRR VS = 2.7 V to 5.5 V 105 125 dB

−40°C ≤ TA ≤ +125°C 100 125 dB
Supply Current/Amplifier I

SY

−40°C ≤ TA ≤ +125°C 190 215 µA
DYNAMIC PERFORMANCE

Slew Rate SR RL = 10 kΩ 0.4 V/µs
Settling Time 0.01% t

S

Overload Recovery Time 0.05 ms
Gain Bandwidth Product GBP 600 kHz
Phase Margin Ø

O

NOISE PERFORMANCE

Voltage Noise e
Voltage Noise Density e

n p-p

n

5 13 µV

15 25 pA

20 50 pA

RL = 10 kΩ, VO = 0.1 V to 1.7 V 110 140 dB

/ΔT

−40°C ≤ T

≤ +125°C 0.03 0.1 µV/°C

A

RL = 100 kΩ to ground 2.68 2.698 V

= 10 kΩ to ground 2.67 2.68 V

L

RL = 100 kΩ to V+ 1.7 5 mV

= 10 kΩ to V+ 14 20 mV

L

±8 mA

IO = 0 150 180 µA

G = ±1, 1 V step, CL = 20 pF, RL = 1 kΩ 5 s

RL = 10 kΩ, RL = 100 kΩ, CL = 20 pF 65 Degrees

f = 0.1 Hz to 10 Hz 2.0 µV p-p
f = 1 kHz 50

nV/√Hz

Rev. 0 | Page 4 of 12