ANALOG DEVICES AD8293G80 Service Manual

Low Cost, Zero-Drift In-Amp

V

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FEATURES

Small package: 8-lead SOT-23
Reduced component count

Incorporates gain resistors and filter resistors
Low offset voltage: 20 μV maximum
Low offset drift: 0.3 μV/°C maximum
Low gain drift: 25 ppm/°C maximum
High CMR: 140 dB typical
Low noise: 0.7 μV p-p from 0.01 Hz to 10 Hz
Single-supply operation: 1.8 V to 5.5 V
Rail-to-rail output
Available in 2 fixed-gain models

APPLICATIONS

Current sensing
Strain gauges
Laser diode control loops
Portable medical instruments
Thermocouple amplifiers

with Filter and Fixed Gain

AD8293G80/AD8293G160

FUNCTIONAL BLOCK DIAGRAM

7 5 6

FILT+V

+5

7 5

S

IN-AMP

R2

REFGND

OUT

R3

5kΩ

ADC OUT

AD8293Gxx

Figure 1.

C2

6

FILT+V

OUT

R2

R3

5kΩ

AD8293Gxx

32

ADC OUT

4

OUTPUT TO ADC
WITH ANTI ALIASING
FILTER

4

C3

+3.3V

ADC

REF

S

+IN

8

R1

IN-AMP

4kΩ

–IN

1

REFGND

32

0.1µF

LOAD

I

1.8V

DC-DC

R

SHUNT

+IN

8

R1

4kΩ

–IN

1

Figure 2. Measuring Current Using the AD8293G80/AD8293G160

07451-001

10µF0.1µF

07451-002

GENERAL DESCRIPTION

The AD8293G80/AD8293G160 are small, low cost, precision
instrumentation amplifiers that have low noise and rail-to-rail
outputs. They are available in two fixed-gain models: 80 and 160.
They incorporate the gain setting resistors and filter resistors,
reducing the number of ancillary components. For example,
only two external capacitors are needed to implement a 2-pole
filter. The AD8293G80/AD8293G160 also feature low offset
voltage, offset drift, and gain drift coupled with high common­mode rejection. They are capable of operating on a supply of

1.8 V to 5.5 V.

With a low offset voltage of 20 µV (AD8293G160B), an offset
voltage drift of 0.3 µV/°C, and a voltage noise of only 0.7 µV p-p
(0.01 Hz to 10 Hz), the AD8293G80/AD8293G160 are ideal
for applications where error sources cannot be tolerated.

Rev. 0

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.

Table 1. AD8293Gxx Models and Gains

Model Gain

AD8293G80 80
AD8293G160 160

Precision instrumentation, position and pressure sensors,
medical instrumentation, and strain gauge amplifiers benefit
from the low noise, low input bias current, and high common­mode rejection. The small footprint and low cost are ideal for
high volume applications.

The small package and low power consumption allow the maxi­mum channel density and the minimum board size required for
portable systems. Designed for ease of use, these instrumentation
amplifiers, unlike more traditional ones, have a buffered reference,
eliminating the need for an additional op amp to set the reference
voltage to midsupply.

The AD8293G80/AD8293G160 are specified over the industrial
temperature range from −40°C to +85°C. The AD8293G80/
AD8293G160 are available in a halogen-free, Pb-free, 8-lead SOT-23.

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: [phone] www.analog.com
Fax: [phone] ©2008 Analog Devices, Inc. All rights reserved.

AD8293G80/AD8293G160

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TABLE OF CONTENTS

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

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

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

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

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

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

Electrical Characteristics ............................................................. 3

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

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

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

Pin Configuration and Function Descriptions ............................. 6

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

REVISION HISTORY

8/08—Revision 0: Initial Version

Theory of Operation ...................................................................... 10

High PSR and CMR ................................................................... 10

1/f Noise Correction .................................................................. 10

Applications Information .............................................................. 11

Overview ..................................................................................... 11

Reference Connection ............................................................... 11

Output Filtering .......................................................................... 11

Clock Feedthrough ..................................................................... 12

Power Supply Bypassing ............................................................ 12

Input Overvoltage Protection ................................................... 12

Outline Dimensions ....................................................................... 13

Ordering Guide .......................................................................... 13

Rev. 0 | Page 2 of 16

AD8293G80/AD8293G160

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SPECIFICATIONS

ELECTRICAL CHARACTERISTICS

VCC = 5.0 V, VCM = −0 V, V
specifications guaranteed by characterization.

Table 2. A Grade

AD8293G80A AD8293G160A
Parameter Symbol Conditions Min Typ Max Min Typ Max Unit

COMMON-MODE REJECTION CMR

NOISE PERFORMANCE

Voltage Noise e

Voltage Noise Density en f = 1 kHz 35 35 nV/√Hz

INPUT CHARACTERISTICS

Input Offset Voltage VOS 9 50 9 50 μV

vs. Temperature ΔVOS/ΔT −40°C ≤ TA ≤ +85°C 0.02 0.3 0.02 0.3 μV/°C
Input Bias Current IB −40°C ≤ TA ≤ +85°C 0.4 2 0.4 2 nA
Input Offset Current IOS 4 4 nA
Input Operating Impedance

Differential 50||1 50||1 MΩ||pF

Common Mode 10||10 10||10 GΩ||pF
Input Voltage Range 0 VCC − 1.7 0 VCC − 1.7 V

DYNAMIC RESPONSE

Small Signal Bandwidth
Slew Rate SR Filter limited Filter limited
Settling Time

2

t

0.1% 500 Hz filter, VO = 2 V step 1.9 1.9 ms

0.01% 2.4 2.4 ms

Internal Clock Frequency 60 60 kHz

GAIN 80 160

Gain Error VO = 0.075 V to 4.925 V 0.3 1 0.3 1 %
Gain Drift −40°C ≤ TA ≤ +85°C 5 25 5 25 ppm/°C
Nonlinearity VO = 0.075 V to 4.925 V 0.003 0.03 0.003 0.03 % FS

OUTPUT CHARACTERISTICS

Output Voltage High VOH

Output Voltage Low VOL 0.075 0.075 V
Short-Circuit Current ISC ±35 ±35 mA

REFERENCE CHARACTERISTICS

V

Range 0.8 VCC − 0.8 0.8 VCC − 0.8 V

REF

REF Pin Current I

POWER SUPPLY

Operating Range 1.8 5.5 1.8 5.5 V
Power Supply Rejection PSR VCC = 1.8 V to 5.5 V, VCM = 0 V 94 120 94 120 dB
Supply Current ISY I

−40°C ≤ TA ≤ +85°C 1.5 1.5 mA

TEMPERATURE RANGE

Specified Range −40 +85 −40 +85 °C

1

Higher bandwidths result in higher noise.

2

Settling time is determined by filter setting.

= 3.3 V, VIN = V

REF

f = 0.01 Hz to 10 Hz 0.7 0.7 μV p-p

n p-p

1

BW Filter limited 500 500 Hz

s

0.01 1 0.01 1 nA

REF

− V

INP

V

CM

−40°C ≤ T

= 0 mA, VIN = 0 V 1.0 1.3 1.0 1.3 mA

O

, TA = 25°C, tested at ADC OUT, unless otherwise noted. Temperature

INN

= 0 V to 3.3 V,

≤ +85°C

A

Rev. 0 | Page 3 of 16

94 140 94 140 dB

−

V

CC

0.075

−

V

CC

0.075

V

AD8293G80/AD8293G160

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VCC = 2.7 V to 5.0 V, VCM = −0 V, V
otherwise noted. Temperature specifications guaranteed by characterization.

Table 3. B Grade (Tested and Guaranteed over a Wider Supply Range to More Stringent Specifications Than the A Grade)

AD8293G80B AD8293G160B
Parameter Symbol Conditions Min Typ Max Min Typ Max Unit

COMMON-MODE REJECTION CMR

NOISE PERFORMANCE

Voltage Noise e
Voltage Noise Density en f = 1 kHz 35 35 nV/√Hz

INPUT CHARACTERISTICS

Input Offset Voltage VOS 5 30 3 20 μV

vs. Temperature ΔVOS/ΔT −40°C ≤ TA ≤ +85°C, VCC = 5 V 0.02 0.3 0.02 0.3 μV/°C

vs. Temperature ΔVOS/ΔT −40°C ≤ TA ≤ +85°C, VCC = 2.7 V 0.01 0.5 0.01 0.5 μV/°C
Input Bias Current IB −40°C ≤ TA ≤ +85°C 0.4 2 0.4 2 nA
Input Offset Current IOS 4 4 nA
Input Operating Impedance

Differential 50||1 50||1 MΩ||pF

Common Mode 10||10 10||10 GΩ||pF
Input Voltage Range 0 VCC − 1.7 0 VCC − 1.7 V

DYNAMIC RESPONSE

Small Signal Bandwidth

1

BW

Slew Rate SR Filter limited Filter limited
Settling Time

2

t

0.1%

0.01% 2.4 2.4 ms

Internal Clock Frequency 60 60 kHz

GAIN 80 160

Gain Error VO = 0.075 V to 4.925 V 0.3 0.5 0.3 0.5 %
Gain Drift −40°C ≤ TA ≤ +85°C 5 25 5 25 ppm/°C
Nonlinearity VO = 0.075 V to 4.925 V 0.003 0.009 0.003 0.009 % FS

OUTPUT CHARACTERISTICS

Output Voltage High VOH

Output Voltage Low VOL 0.075 0.075 V
Short-Circuit Current ISC V
V

REFERENCE CHARACTERISTICS

V

Range 0.8 VCC − 0.8 0.8 VCC − 0.8 V

REF

REF Pin Current I

POWER SUPPLY

Operating Range 1.8 5.5 1.8 5.5 V
Power Supply Rejection PSR VCC = 1.8 V to 5.5 V, VCM = 0 V 100 120 100 120 dB
Supply Current ISY I

−40°C ≤ TA ≤ +85°C 1.5 1.5 mA

TEMPERATURE RANGE

Specified Range −40 +85 −40 +85 °C

1

Higher bandwidths result in higher noise.

2

Settling time is determined by filter setting.

= VCC/2, VIN = V

REF

= 5 V, VCM = 0 V to 3.3 V;

V

CC

−40°C ≤ T
= 2.7 V, VCM = 0 V to 1 V;

V

CC

−40°C ≤ T

f = 0.01 Hz to 10 Hz 0.7 0.7 μV p-p

n p-p

Filter limited; measured at

− V

INP

≤ +85°C

A

≤ +85°C

A

, TA = 25°C, tested at OUT with 10 kΩ load and ADC OUT, unless

INN

110 140 110 140 dB

106 140 106 140 dB

500 500 Hz

ADC OUT

s

500 Hz filter, V

= 2 V step;

O

1.9 1.9 ms

measured at ADC OUT

V

CC

0.075

= 5 V ±35 ±35 mA

CC

= 2.7 V ±25 ±25 mA

CC

0.01 1 0.01 1 nA

REF

= 0 mA, VIN = 0 V 1.0 1.3 1.0 1.3 mA

O

Rev. 0 | Page 4 of 16

V

0.075

−

V

−

CC

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ABSOLUTE MAXIMUM RATINGS

Table 4.

Parameter Rating

Supply Voltage 6 V
Input Voltage +V
Differential Input Voltage1 ±V
Output Short-Circuit Duration to GND Indefinite
Storage Temperature Range (RJ Package) −65°C to +150°C
Operating Temperature Range −40°C to +85°C
Junction Temperature Range (RJ Package) −65°C to +150°C
Lead Temperature (Soldering, 10 sec) 300°C

1

Differential input voltage is limited to ±5.0 V, the supply voltage, or

whichever is less.

SUPPLY

SUPPLY

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 the worst-case conditions, that is, a device
soldered in a circuit board for surface-mount packages.

Table 5.

Package Type θ

8-Lead SOT-23 (RJ) 211.5 91.99 °C/W

1

θJA is specified for the nominal conditions, that is, θJA is specified for the

device soldered on a circuit board.

1

θJC Unit

JA

ESD CAUTION

Rev. 0 | Page 5 of 16