ANALOG DEVICES AD8227 Service Manual

Wide Supply Range, Rail-to-Rail

FEATURES

Gain set with 1 external resistor

Gain range: 5 to 1000 Input voltage goes below ground Inputs protected beyond supplies Very wide power supply range

Single supply: 2.2 V to 36 V

Dual supply: ±1.5 V to ±18 V Bandwidth (G = 5): 250 kHz CMRR (G = 5): 100 dB minimum (B Grade) Input noise: 24 nV/√Hz Typical supply current: 350 μA Specified temperature: −40°C to +125°C 8-lead SOIC and MSOP packages

APPLICATIONS

Industrial process controls Bridge amplifiers Medical instrumentation Portable data acquisition Multichannel systems

Output Instrumentation Amplifier

AD8227

PIN CONFIGURATION

AD8227

1

–IN

2

R

G

3

R

G

4

+IN

TOP VIEW

(Not to Scale)

Figure 1.

Table 1. Instrumentation Amplifiers by Category

General Purpose

Zero Drift

Military Grade

AD8220 AD8231 AD620 AD627 AD8250 AD8221 AD8290 AD621 AD623 AD8251 AD8222 AD8293 AD524 AD8223 AD8253 AD8224 AD8553 AD526 AD8226 AD8228 AD8556 AD624 AD8227 AD8295 AD8557

1

See www.analog.com for the latest selection of instrumentation amplifiers.

8

+V

S

7

V

OUT

6

REF

5

–V

S

Low Power

07759-001

1

High Speed PGA

GENERAL DESCRIPTION

The AD8227 is a low cost, wide supply range instrumentation amplifier that requires only one external resistor to set any gain between 5 and 1000.

The AD8227 is designed to work with a variety of signal voltages. A wide input range and rail-to-rail output allow the signal to make full use of the supply rails. Because the input range can also go below the negative supply, small signals near ground can be amplified without requiring dual supplies. The AD8227 operates on supplies ranging from ±1.5 V to ±18 V (2.2 V to 36 V single supply).

The robust AD8227 inputs are designed to connect to realworld sensors. In addition to its wide operating range, the AD8227 can handle voltages beyond the rails. For example, with a ±5 V supply, the part is guaranteed to withstand ±35 V at the input with no damage. Minimum as well as maximum input bias currents are specified to facilitate open wire detection.

The AD8227 is ideal for multichannel, space-constrained applications. With its MSOP package and 125°C temperature rating, the AD8227 thrives in tightly packed, zero airflow designs.

The AD8227 is available in 8-pin MSOP and SOIC packages. It is fully specified for −40°C to +125°C operation.

For a similar instrumentation amplifier with a gain range of 1 to 1000, see the AD8226.

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.

AD8227

REVISION HISTORY

5/09—Revision 0: Initial Version

Gain Selection ............................................................................. 19

Reference Terminal .................................................................... 20

Input Voltage Range ................................................................... 20

Layout .......................................................................................... 20

Input Bias Current Return Path ............................................... 21

Input Protection ......................................................................... 21

Radio Frequency Interference (RFI) ........................................ 21

Applications Information .............................................................. 22

Differential Drive ....................................................................... 22

Precision Strain Gage ................................................................. 22

Driving an ADC ......................................................................... 23

Outline Dimensions ....................................................................... 24

Ordering Guide .......................................................................... 24

Rev. 0 | Page 2 of 24

AD8227

SPECIFICATIONS

+VS = +15 V, −VS = −15 V, V

Table 2.

Test Conditions/ A Grade B Grade Parameter Comments Min Typ Max Min Typ Max Unit

COMMON-MODE REJECTION RATIO VCM = −10 V to +10 V

DC to 60 Hz

G = 5 90 100 dB G = 10 96 105 dB G = 100 105 110 dB G = 1000 105 110 dB

5 kHz

G = 5 80 80 dB G = 10 86 86 dB G = 100 86 86 dB G = 1000 86 86 dB

NOISE

Voltage Noise, 1 kHz

Input Voltage Noise, eNI 24 25 24 25 nV/√Hz Output Voltage Noise, eNO 310 315 310 315 nV/√Hz

RTI f = 0.1 Hz to 10 Hz

G = 5 1.5 1.5 μV p-p G = 10 0.9 0.9 μV p-p

G = 100 to 1000 0.5 0.5 μV p-p Current Noise f = 1 kHz 100 100 fA/√Hz f = 0.1 Hz to 10 Hz 3 3 pA p-p

VOLTAGE OFFSET

Input Offset, V

V

OSI

Average Temperature Drift TA = −40°C to +125°C 0.2 2 0.2 1 μV/°C Output Offset, V

V

OSO

Average Temperature Drift TA = −40°C to +125°C 2 10 2 5 μV/°C Offset RTI vs. Supply (PSR) VS = ±5 V to ±15 V

G = 5 90 100 dB

G = 10 96 105 dB

G = 100 105 110 dB

G = 1000 105 110 dB

INPUT CURRENT

Input Bias Current

1

T

Average Temperature Drift TA = −40°C to +125°C 70 70 pA/°C Input Offset Current TA = +25°C 1.5 1.5 nA T T

Average Temperature Drift TA = −40°C to +125°C 5 5 pA/°C

REFERENCE INPUT

RIN 60 60 kΩ IIN 12 12 μA Voltage Range −VS +VS −VS +VS V Reference Gain to Output 1 1 V/V Reference Gain Error 0.01 0.01 %

= 0 V, TA = 25°C, G = 5, RL = 10 k, specifications referred to input, unless otherwise noted.

REF

Tot al noise:

eN = √(e

2

+ (eNO/G)2)

NI

Total offset voltage: VOS = V

+ (V

OSO

/G)

OSI

= ±5 V to ±15 V 200 100 μV

S

= ±5 V to ±15 V 1000 500 μV

S

= +25°C 5 20 27 5 20 27 nA

A

= +125°C 5 15 25 5 15 25 nA

A

= −40°C 5 30 35 5 30 35 nA

A

= +125°C 1.5 1.5 nA

A

= −40°C 2 2 nA

A

Rev. 0 | Page 3 of 24

AD8227

Test Conditions/ A Grade B Grade Parameter Comments Min Typ Max Min Typ Max Unit

DYNAMIC RESPONSE

Small Signal −3 dB Bandwidth

G = 5 250 250 kHz G = 10 200 200 kHz G = 100 50 50 kHz G = 1000 5 5 kHz

Settling Time 0.01% 10 V step

G = 5 14 14 μs G = 10 15 15 μs G = 100 35 35 μs G = 1000 275 275 μs

Slew Rate

GAIN

Gain Range 5 1000 5 1000 V/V Gain Error V

Gain Nonlinearity V

Gain vs. Temperature TA = −40°C to +125°C

INPUT VS = ±1.5 V to +36 V

Impedance

Operating Voltage Range T T Overvoltage Range TA = −40°C to +125°C +VS − 40 −VS + 40 +VS − 40 −VS + 40 V

OUTPUT

Output Swing

Short-Circuit Current 13 13 mA

POWER SUPPLY

Operating Range Dual-supply operation ±1.5 ±18 ±1.5 ±18 V Quiescent Current TA = +25°C 350 425 350 425 μA T T T

TEMPERATURE RANGE −40 +125 −40 +125 °C

1

The input stage uses pnp transistors, so input bias current always flows into the part.

2

At high gains, the part is bandwidth limited rather than slew rate limited.

3

For G > 5, gain error specifications do not include the effects of External Resistor RG.

4

Input voltage range of the AD8227 input stage. The input range depends on the common-mode voltage, differential voltage, gain, and reference voltage. See the

2

G = 5 to 100 0.8 0.8 V/μs

3

G = 5 + (80 kΩ/R

= −10 V to +10 V

OUT

)

G

G = 5 0.04 0.02 % G = 10 to 1000 0.3 0.15 %

= −10 V to +10 V

OUT

G = 5 RL ≥ 2 kΩ 10 10 ppm G = 10 RL ≥ 2 kΩ 15 15 ppm G = 100 RL ≥ 2 kΩ 15 50 ppm G = 1000 RL ≥ 2 kΩ 750 150 ppm

G = 5 5 5 ppm/°C G > 5 −100 −100 ppm/°C

Differential 0.8||2 0.8||2 GΩ||pF Common Mode 0.4||2 0.4||2 GΩ||pF

4

TA = +25°C −VS − 0.1 +VS − 0.8 −VS − 0.1 +VS − 0.8 V

= +125°C −VS − 0.05 +VS − 0.6 −VS − 0.05 +VS − 0.6 V

A

= −40°C −VS − 0.15 +VS − 0.9 −VS − 0.15 +VS − 0.9 V

A

RL = 10 kΩ to ground TA = −40°C to +85°C −VS + 0.2 +VS − 0.2 −VS + 0.2 +VS − 0.2 V T

= +85°C to +125°C −VS + 0.2 +VS − 0.3 −VS + 0.2 +VS − 0.3 V

A

RL = 100 kΩ to ground TA = −40°C to +125°C −VS + 0.1 +VS − 0.1 −VS + 0.1 +VS − 0.1 V

= −40°C 250 325 250 325 μA

A

= +85°C 450 525 450 525 μA

A

= +125°C 525 600 525 600 μA

A

section for more information. Input Voltage Range

Rev. 0 | Page 4 of 24

AD8227

+VS = 2.7 V, −VS = 0 V, V

Table 3.

Test Conditions/ A Grade B Grade Parameter Comments Min Typ Max Min Typ Max Unit

COMMON-MODE REJECTION RATIO VCM = 0 V to 1.7 V

DC to 60 Hz

G = 5 90 100 dB

G = 10 96 105 dB

G = 100 105 110 dB

G = 1000 105 110 dB 5 kHz

G = 5 80 80 dB

G = 10 86 86 dB

G = 100 86 86 dB

G = 1000 86 86 dB

NOISE

Voltage Noise, 1 kHz

Input Voltage Noise, eNI 25 28 25 28 nV/√Hz

Output Voltage Noise, eNO 310 330 310 330 nV/√Hz RTI f = 0.1 Hz to 10 Hz

G = 5 1.5 1.5 μV p-p

G = 10 0.8 0.8 μV p-p

G = 100 to 1000 0.5 0.5 μV p-p Current Noise f = 1 kHz 100 100 fA/√Hz f = 0.1 Hz to 10 Hz 3 3 pA p-p

VOLTAGE OFFSET

Input Offset, V

V

OSI

Average Temperature Drift TA = −40°C to +125°C 0.2 2 0.2 1 μV/°C Output Offset, V

OSO

Average Temperature Drift TA = −40°C to +125°C 2 10 2 5 μV/°C Offset RTI vs. Supply (PSR) VS = 0 V to 1.7 V

G = 5 90 100 dB

G = 10 96 105 dB

G = 100 105 110 dB

G = 1000 105 110 dB

INPUT CURRENT

Input Bias Current

1

T T

Average Temperature Drift TA = −40°C to +125°C 70 70 pA/°C Input Offset Current TA = +25°C 1.5 1.5 nA T T

Average Temperature Drift TA = −40°C to +125°C 5 5 pA/°C

REFERENCE INPUT

RIN 60 60 kΩ IIN 12 12 μA Voltage Range −VS +VS −VS +VS V Reference Gain to Output 1 1 V/V Reference Gain Error 0.01 0.01 %

= 0 V, TA = 25°C, G = 5, RL = 10 k, specifications referred to input, unless otherwise noted.

REF

Tot al noise:

e

= √(e

N

2

+ (eNO/G)2)

NI

Total offset voltage:

= V

V

T

+ (V

OS

OSI

OSO

= 0 V to 1.7 V 200 100 μV

S

= 0 V to 1.7 V 1000 500 μV

S

= +25°C 5 20 27 5 20 27 nA

A

= +125°C 5 15 25 5 15 25 nA

A

= −40°C 5 30 35 5 30 35 nA

A

= +125°C 1.5 1.5 nA

A

= −40°C 2 2 nA

A

/G)

Rev. 0 | Page 5 of 24

AD8227

Test Conditions/ A Grade B Grade Parameter Comments Min Typ Max Min Typ Max Unit

DYNAMIC RESPONSE

Small Signal −3 dB Bandwidth

G = 5 250 250 kHz G = 10 200 200 kHz G = 100 50 50 kHz G = 1000 5 5 kHz

Settling Time 0.01% 2 V step

G = 5 6 6 μs G = 10 6 6 μs G = 100 30 30 μs G = 1000 275 275 μs

Slew Rate

GAIN

Gain Range 5 1000 5 1000 V/V Gain Error

Gain vs. Temperature TA = −40°C to +125°C

INPUT

Impedance

Operating Voltage Range T T Overvoltage Range TA = −40°C to +125°C +VS − 40 −VS + 40 +VS − 40 −VS + 40 V

OUTPUT

Output Swing TA = −40°C to +125°C

Short-Circuit Current 13 13 mA

POWER SUPPLY

Operating Range Single-supply operation 2.2 36 2.2 36 V Quiescent Current +VS = 2.7 V T T T T

TEMPERATURE RANGE −40 +125 −40 +125 °C

1

Input stage uses pnp transistors, so input bias current always flows into the part.

2

At high gains, the part is bandwidth limited rather than slew rate limited.

3

For G > 5, gain error specifications do not include the effects of External Resistor RG.

4

Input voltage range of the AD8227 input stage. The input range depends on the common-mode voltage, differential voltage, gain, and reference voltage. See the

2

G = 5 to 10 0.6 0.6 V/μs

3

G = 5 + (80 kΩ/R

G = 5 V G = 10 to 1000 V

= 0.8 V to 1.8 V 0.04 0.04 %

OUT

= 0.2 V to 2.5 V 0.3 0.3 %

OUT

)

G

G = 5 5 5 ppm/°C G > 5 −100 −100 ppm/°C

= 0 V; +VS = 2.7 V to

−V

S

36 V

Differential 0.8||2 0.8||2 GΩ||pF Common Mode 0.4||2 0.4||2 GΩ||pF

4

TA = +25°C −0.1 +VS − 0.7 −0.1 +VS − 0.7 V

= −40°C −0.15 +VS − 0.9 −0.15 +VS − 0.9 V

A

= +125°C −0.05 +VS − 0.6 −0.05 +VS − 0.6 V

A

RL = 2 kΩ to 1.35 V 0.2 +VS − 0.2 0.2 +VS − 0.2 V RL = 10 kΩ to 1.35 V 0.1 +VS − 0.1 0.1 +VS − 0.1 V

= +25°C 325 400 325 400 μA

A

= −40°C 250 325 250 325 μA

A

= +85°C 425 500 425 500 μA

A

= +125°C 475 550 475 550 μA

A

section for more information. Input Voltage Range

Rev. 0 | Page 6 of 24

AD8227

ABSOLUTE MAXIMUM RATINGS

Table 4.

Parameter Rating

Supply Voltage ±18 V Output Short-Circuit Current Indefinite Maximum Voltage at −IN or +IN −VS + 40 V Minimum Voltage at −IN or +IN +VS − 40 V REF Voltage ±VS Storage Temperature Range −65°C to +150°C Operating Temperature Range −40°C to +125°C Maximum Junction Temperature 140°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

θJA is specified for a device in free air.

Table 5.

Package θJA Unit

8-Lead MSOP, 4-Layer JEDEC Board 135 °C/W 8-Lead SOIC, 4-Layer JEDEC Board 121 °C/W

ESD CAUTION

Rev. 0 | Page 7 of 24

AD8227

PIN CONFIGURATION AND FUNCTION DESCRIPTIONS

AD8227

1

–IN

2

R

G

3

R

G

4

+IN

TOP VIEW

(Not to Scale)

Figure 2. Pin Configuration

Table 6. Pin Function Descriptions

Pin No. Mnemonic Description

1 −IN Negative Input. 2, 3 RG Gain Setting Pins. Place a gain resistor between these two pins. 4 +IN Positive Input. 5 −VS Negative Supply. 6 REF Reference. This pin must be driven by low impedance. 7 V

Output.

OUT

8 +VS Positive Supply.

8

+V

S

7

V

OUT

6

REF

5

–V

S

07759-002

Rev. 0 | Page 8 of 24

ANALOG DEVICES AD8227 Service Manual

FEATURES

APPLICATIONS

PIN CONFIGURATION

GENERAL DESCRIPTION

TABLE OF CONTENTS

REVISION HISTORY

SPECIFICATIONS

ABSOLUTE MAXIMUM RATINGS

THERMAL RESISTANCE

ESD CAUTION

PIN CONFIGURATION AND FUNCTION DESCRIPTIONS