Precision, Dual-Channel
Instrumentation Amplifier
AD8222
FEATURES
Two channels in small 4 mm × 4 mm LFCSP
Gain set with 1 resistor per amplifier (G = 1 to 10,000)
Low noise
8 nV/√Hz at 1 kHz
0.25 μV p-p (0.1 Hz to 10 Hz)
High accuracy dc performance (B grade)
60 μV maximum input offset voltage
0.3 μV/°C maximum input offset drift
1.0 nA maximum input bias current
126 dB minimum CMRR (G = 100)
Excellent ac performance
140 kHz bandwidth (G = 100)
13 μs settling time to 0.001%
Differential output option (single channel)
Fully specified
Adjustable common-mode output
Supply range: ±2.3 V to ±18 V
FUNCTIONAL BLOCK DIAGRAM
OUT1
OUT2
14
+V
S
16
15
–IN1
RG1
RG1
+IN1
AD8222
1
2
3
4
12
11
10
9
–V
S
13
–IN2
RG2
RG2
+IN2
5
6
7
8
05947-001
+V
S
REF1
Figure 1. 4 mm × 4 mm LFCSP
Table 1. Instrumentation Amplifiers by Category
1
General
Purpose
AD8220
AD8221
AD8222
AD8224
AD8228
AD8295
Zero
Drift
AD8231
AD8290
AD8293
AD8553
AD8556
AD8557
Military
Grade
AD620
AD621
AD524
AD526
AD624
Low
Power
AD8235
AD8236
AD627
AD623
AD8223
AD8226
AD8227
High Speed
PGA
AD8250
AD8251
AD8253
APPLICATIONS
Multichannel data acquisition for
ECG and medical instrumentation
Industrial process controls
Wheatstone bridge sensors
Differential drives for
High resolution input ADCs
Remote sensors
1
See
www.analog.com
for the latest selection of instrumentation amplifiers.
GENERAL DESCRIPTION
The AD8222 is a dual-channel, high performance instrumentation
amplifier that requires only one external resistor per amplifier
to set gains of 1 to 10,000.
The AD8222 is the first dual-instrumentation amplifier in the
small 4 mm × 4mm LFCSP. It requires the same board area as a
typical single instrumentation amplifier. The smaller package
allows a 2× increase in channel density and a lower cost per
channel, all with no compromise in performance.
The AD8222 can also be configured as a single-channel, differen-
tial output instrumentation amplifier. Differential outputs provide
high noise immunity, which can be useful when the output
signal must travel through a noisy environment, such as with
remote sensors. The configuration can also be used to drive
differential input ADCs.
Rev. A
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.
The AD8222 maintains a minimum CMRR of 80 dB to 4 kHz
for all grades at G = 1. High CMRR over frequency allows the
AD8222 to reject wideband interference and line harmonics,
greatly simplifying filter requirements. The AD8222 also has a
typical CMRR drift over temperature of just 0.07 μV/V/°C at G = 1.
The AD8222 operates on both single and dual supplies and only
requires 2.2 mA maximum supply current for both amplifiers.
It is specified over the industrial temperature range of −40°C to
+85°C and is fully RoHS compliant.
For a single-channel version, see the
AD8221.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
www.analog.com
Fax: 781.461.3113 ©2006–2010 Analog Devices, Inc. All rights reserved.
REF2
–V
S
AD8222
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications ....................................................................................... 1
Functional Block Diagram .............................................................. 1
General Description ......................................................................... 1
Revision History ............................................................................... 2
Specifications..................................................................................... 3
Absolute Maximum Ratings............................................................ 6
Thermal Resistance ...................................................................... 6
ESD Caution .................................................................................. 6
Pin Configuration and Function Descriptions ............................. 7
Typical Performance Characteristics ............................................. 8
Theory of Operation ...................................................................... 15
Amplifier Architecture .............................................................. 15
Gain Selection ............................................................................. 15
Reference Terminal .................................................................... 16
Package Considerations ............................................................. 16
Layout .......................................................................................... 16
Input Bias Current Return Path ............................................... 17
Input Protection ......................................................................... 18
RF Interference ........................................................................... 18
Common-Mode Input Voltage Range ..................................... 18
Applications Information .............................................................. 19
Differential Output .................................................................... 19
Driving a Differential Input ADC ............................................ 20
Precision Strain Gage ................................................................. 20
Driving Cabling .......................................................................... 21
Outline Dimensions ....................................................................... 22
Ordering Guide .......................................................................... 23
REVISION HISTORY
2/10—Rev. 0 to Rev. A
Added LFCSP_VQ, CP-16-13 Package ............................ Universal
Changes to Features Section and Table 1 ...................................... 1
Changed V
IN+
to V
+IN
, V
IN−
to V
−IN
, and T to T
A
Throughout ..... 3
Change to Reference Input Parameter, Table 2 ............................. 4
Changed Output Short-Circuit Current to Output Short-Circuit
Duration, Table 5 .............................................................................. 6
Changes to Thermal Resistance Section and Table 6................... 6
Changes to Figure 2 .......................................................................... 7
Changes to Figure 19 ...................................................................... 10
Changes to Figure 43 ...................................................................... 14
Changes to Reference Terminal Section, Figure 45, and Package
Considerations Section .................................................................. 16
Deleted Thermal Pad Section ....................................................... 16
Added Package Without Thermal Pad and Package with
Thermal Pad Sections .................................................................... 16
Changes to Figure 46...................................................................... 17
Deleted Solder Wash Section ........................................................ 17
Changes to RFI and Antialising Filter Section ........................... 20
Updated Outline Dimensions ....................................................... 22
Changes to Ordering Guide .......................................................... 23
7/06—Revision 0: Initial Version
Rev. A | Page 2 of 24
AD8222
SPECIFICATIONS
V
S
= ±15 V, V
REF
= 0 V, T
A
= 25°C, G = 1, R
L
= 2 kΩ, unless otherwise noted.
Table 2. Single-Ended and Differential
1
Output Configuration
Parameter
COMMON-MODE REJECTION
RATIO (CMRR)
CMRR DC to 60 Hz
G=1
G = 10
G = 100
G = 1000
CMRR at 4 kHz
G=1
G = 10
G = 100
G = 1000
CMRR Drift
NOISE
Voltage Noise, 1 kHz
Input Voltage Noise, e
NI
Output Voltage Noise, e
NO
RTI
G=1
G = 10
G = 100 to 1000
Current Noise
VOLTAGE OFFSET
Input Offset, V
OSI
Over Temperature
Average TC
Output Offset, V
OSO
Over Temperature
Average TC
Offset RTI vs. Supply (PSR)
G=1
G = 10
G = 100
G = 1000
INPUT CURRENT (PER CHANNEL)
Input Bias Current, I
BIAS
Over Temperature
Average TC
Input Offset Current, I
OFFSET
Over Temperature
Average TC
Conditions
V
CM
= –10 V to +10 V
1 kΩ source imbalance
80
100
120
130
80
90
100
100
T
A
= −40°C to +85°C, G = 1
RTI noise = √(e
NI2
+ (e
NO
/G)
2
)
V
+IN
, V
−IN
, V
REF
= 0 V
V
+IN
, V
−IN
, V
REF
= 0 V
f = 0.1 Hz to 10 Hz
2
0.5
0.25
40
6
120
150
0.4
500
0.8
9
90
110
124
130
110
120
130
140
0.5
T
A
= −40°C to +85°C
1
0.2
T
A
= −40°C to +85°C
1
2.0
3.0
1
1.5
94
114
130
140
110
130
140
150
0.2
1
0.1
0.5
1.0
1.5
0.5
0.6
2
0.07
86
106
126
140
80
100
110
110
0.07
dB
dB
dB
dB
dB
dB
dB
dB
μV/V/°C
Min
A Grade
Typ
Max
Min
B Grade
Typ
Max
Unit
8
75
2
0.5
0.25
40
6
8
75
nV/√Hz
nV/√Hz
μV p-p
μV p-p
μV p-p
fA/√Hz
pA p-p
f = 1 kHz
f = 0.1 Hz to 10 Hz
RTI V
OS
= (V
OSI
) + (V
OSO
/G)
V
S
= ±5 V to ±15 V
T
A
= −40°C to +85°C
V
S
= ±5 V to ±15 V
T
A
= −40°C to +85°C
V
S
= ±2.3 V to ±18 V
60
80
0.3
350
0.5
5
μV
μV
μV/°C
μV
mV
μV/°C
dB
dB
dB
dB
nA
nA
pA/°C
nA
nA
pA/°C
Rev. A | Page 3 of 24
AD8222
Parameter
REFERENCE INPUT
R
IN
I
IN
Voltage Range
Reference Gain to Output
Reference Gain Error
GAIN
Gain Range
Gain Error
G=1
G = 10
G = 100
G = 1000
Gain Nonlinearity
G=1
G = 10
G = 100
Gain vs. Temperature
G=1
G > 1
2
INPUT
Input Impedance
Differential
Common Mode
Input Operating Voltage Range
3
Over Temperature
Input Operating Voltage Range
3
Over Temperature
OUTPUT
Output Swing
Over Temperature
Output Swing
Over Temperature
Short-Circuit Current
POWER SUPPLY
Operating Range
Quiescent Current (per Amplifier)
Over Temperature
TEMPERATURE RANGE
Specified Performance
Operational
4
1
2
Conditions
Min
A Grade
Typ
Max
20
50
Min
B Grade
Typ
Max
20
50
Unit
kΩ
μA
V
V/V
%
V/V
%
%
%
%
ppm
ppm
ppm
ppm/°C
ppm/°C
V
+IN
, V
−IN
, V
REF
= 0 V
−V
S
60
+V
S
−V
S
1
0.01
60
+V
S
1
0.01
G = 1 + (49.4 kΩ/R
G
)
1
V
OUT
± 10 V
0.05
0.3
0.3
0.3
V
OUT
= –10 V to +10 V
3
7
7
3
10
20
20
10
−50
10000
1
10000
0.02
0.15
0.15
0.15
1
7
7
2
5
20
20
5
−50
100||2
100||2
V
S
= ±2.3 V to ±5 V
T
A
= −40°C to +85°C
V
S
= ±5 V to ±18 V
T
A
= −40°C to +85°C
R
L
= 10 kΩ
V
S
= ±2.3 V to ±5 V
T
A
= −40°C to +85°C
V
S
= ±5 V to ±18 V
T
A
= −40°C to +85°C
−V
S
+ 1.9
−V
S
+ 2.0
−V
S
+ 1.9
−V
S
+ 2.0
−V
S
+ 1.1
−V
S
+ 1.4
−V
S
+ 1.2
−V
S
+ 1.6
18
V
S
= ±2.3 V to ±18 V
T
A
= −40°C to +85°C
−40
−40
±2.3
0.9
1
±18
1.1
1.2
+85
+125
±2.3
+V
S
− 1.1
+V
S
− 1.2
+V
S
− 1.2
+V
S
− 1.2
+V
S
− 1.2
+V
S
− 1.3
+V
S
− 1.4
+V
S
− 1.5
−V
S
+ 1.9
−V
S
+ 2.0
−V
S
+ 1.9
−V
S
+ 2.0
−V
S
+ 1.1
−V
S
+ 1.4
−V
S
+ 1.2
−V
S
+ 1.6
100||2
100||2
+V
S
− 1.1
+V
S
− 1.2
+V
S
− 1.2
+V
S
− 1.2
+V
S
− 1.2
+V
S
− 1.3
+V
S
− 1.4
+V
S
− 1.5
18
±18
1.1
1.2
+85
+125
GΩ||pF
GΩ||pF
V
V
V
V
V
V
V
V
mA
V
mA
mA
°C
°C
0.9
1
−40
−40
Refers to differential configuration shown in Figure 49.
Does not include the effects of external resistor, R
G
.
3
One input grounded. G = 1.
4
See the Typical Performance Characteristics section for expected operation between 85°C and 125°C.
Rev. A | Page 4 of 24
AD8222
V
S
= ±15 V, V
REF
= 0 V, T
A
= 25°C, R
L
= 2 kΩ, unless otherwise noted.
Table 3. Single-Ended Output Configuration—Dynamic Performance (Both Amplifiers)
Parameter
DYNAMIC RESPONSE
Small Signal −3 dB Bandwidth
G=1
G = 10
G = 100
G = 1000
Settling Time 0.01%
G = 1 to 100
G = 1000
Settling Time 0.001%
G = 1 to 100
G = 1000
Slew Rate
Conditions
Min
A Grade
Typ
Max
Min
B Grade
Typ
Max
Unit
1200
750
140
15
10 V step
10
80
10 V step
13
110
2
2.5
1200
750
140
15
10
80
13
110
2
2.5
kHz
kHz
kHz
kHz
μs
μs
μs
μs
V/μs
V/μs
G=1
G = 5 to 1000
1.5
2
1.5
2
Table 4. Differential Output Configuration
1
—Dynamic Performance
Parameter
DYNAMIC RESPONSE
Small Signal −3 dB Bandwidth
G=1
G = 10
G = 100
G =1000
Settling Time 0.01%
G = 1 to 100
G = 1000
Settling Time 0.001%
G = 1 to 100
G = 1000
Slew Rate
Conditions
Min
A Grade
Typ
Max
Min
B Grade
Typ
Max
Unit
1000
650
140
15
10 V step
15
80
10 V step
18
110
2
2.5
1000
650
140
15
15
80
18
110
2
2.5
kHz
kHz
kHz
kHz
μs
μs
μs
μs
V/μs
V/μs
G=1
G = 5 to 1000
1.5
2
1.5
2
1
Refers to differential configuration shown in Figure 49.
Rev. A | Page 5 of 24
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