Zero Drift, Digitally Programmable
A
FEATURES
Digitally/pin-programmable gain
G = 1, 2, 4, 8, 16, 32, 64, or 128
Specified from −55°C to +125°C
50 nV/°C maximum input offset drift
10 ppm/°C maximum gain drift
Excellent dc performance
80 dB minimum CMR, G = 1
15 µV maximum input offset voltage
500 pA maximum bias current
0.7 µV p-p noise (0.1 Hz to 10 Hz)
Good ac performance
2.7 MHz bandwidth, G = 1
1.1 V/s slew rate
Rail-to-rail output
Shutdown/multiplex
Extra op amp
Single-supply range: 3 V to 6 V
Dual-supply range: ±1.5 V to ±3 V
ENHANCED PRODUCT FEATURES
Supports defense and aerospace applications (AQEC
standard)
Military temperature range (−55°C to +125°C)
Controlled manufacturing baseline
One assembly/test site
One fabrication site
Enhanced product change notification
Qualification data available on request
Instrumentation Amplifier
AD8231-EP
FUNCTIONAL BLOCK DIAGRAM
A216A115A014CS
13
1
NC
LOGIC
2
–INA
+IN
NC
3
4
IN-AMP
AD8231-EP
5
SDN
OP
AMP
6
+INB
Figure 1.
7
–INB
Table 1. Instrumentation and Difference Amplifiers by
Category
High
Performance
AD8221 AD6231 AD628 AD620 AD6271 AD82311
AD82201 AD85531 AD629 AD621 AD8250
AD8222 AD524 AD8251
AD82241 AD526 AD85551
AD624 AD85561
AD85571
1
Rail-to-rail output.
Low
Cost
High
Voltage
Mil
Grade
12
+V
S
11
–V
S
10
OUTA
9
REF
8
09707-001
OUTB
Low
Power
Digital
Gain
GENERAL DESCRIPTION
The AD8231-EP is a low drift, rail-to-rail, instrumentation
amplifier with software-programmable gains of 1, 2, 4, 8, 16, 32, 64,
or 128. The gains are programmed via digital logic or pin
strapping.
The AD8231-EP is ideal for applications that require precision
performance over a wide temperature range, such as industrial
temperature sensing and data logging. Because the gain setting
resistors are internal, maximum gain drift is only 10 ppm/°C for
gains of 1 to 32. Because of the auto-zero input stage, maximum
input offset is 15 μV and maximum input offset drift is just
50 nV/°C. CMRR is 80 dB for G = 1, increasing to 110 dB at
higher gains.
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.
The AD8231-EP also includes an uncommitted op amp that can
be used for additional gain, differential signal driving, or filtering.
Like the in-amp, the op amp has an auto-zero architecture, railto-rail input, and rail-to-rail output.
The AD8231-EP includes a shutdown feature that reduces current
to a maximum of 1 μA. In shutdown, both amplifiers also have
a high output impedance, which allows easy multiplexing of
multiple amplifiers without additional switches.
The AD8231-EP is specified over the military temperature
range of −55°C to +125°C. It is available in a 4 mm × 4 mm 16lead LFCSP.
Additional application and technical information can be found
in the AD8231 data sheet.
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 ©2011 Analog Devices, Inc. All rights reserved.
AD8231-EP
TABLE OF CONTENTS
Features.............................................................................................. 1
Enhanced Product Features ............................................................ 1
Functional Block Diagram .............................................................. 1
General Description ......................................................................... 1
Revision History ............................................................................... 2
Specifications..................................................................................... 3
Absolute Maximum Ratings............................................................ 7
Thermal Resistance ...................................................................... 7
Maximum Power Dissipation ..................................................... 7
REVISION HISTORY
5/11—Revision 0: Initial Version
ESD Caution...................................................................................7
Pin Configuration and Function Descriptions..............................8
Typical Performance Characteristics ..............................................8
Instrumentation Amplifier Performance Curves......................9
Operational Amplifier Performance Curves .......................... 15
Performance Curves Valid for Both Amplifiers ..................... 17
Outline Dimensions....................................................................... 18
Ordering Guide .......................................................................... 18
Rev. 0 | Page 2 of 20
AD8231-EP
SPECIFICATIONS
VS = 5 V, V
Table 2.
Parameter Test Conditions/Comments Min Typ Max Unit
INSTRUMENTATION AMPLIFIER
Offset Voltage VOS RTI = V
Input Offset, V
Output Offset, V
Input Currents
Input Bias Current 250 500 pA
T
Input Offset Current 20 100 pA
T
Gains 1, 2, 4, 8, 16, 32, 64, or 128
Gain Error
Gain Drift TA = −55°C to +125°C
Linearity 0.2 V to 4.8 V, 10 kΩ load 3 ppm
CMRR
G = 1 80 dB
G = 2 86 dB
G = 4 92 dB
G = 8 98 dB
G = 16 104 dB
G = 32 110 dB
G = 64 110 dB
G = 128 110 dB
Noise en = √(e
Input Voltage Noise, eni f = 1 kHz 32 nV/√Hz
f = 1 kHz, TA = −55°C 27 nV/√Hz
f = 1 kHz, TA = 125°C 39 nV/√Hz
f = 0.1 Hz to 10 Hz 0.7 μV p-p
Output Voltage Noise, eno f = 1 kHz 58 nV/√Hz
f = 1 kHz, TA = −55°C 50 nV/√Hz
f = 1 kHz, TA = 125°C 70 nV/√Hz
f = 0.1 Hz to 10 Hz 1.1 μV p-p
Current Noise f = 10 Hz 20 fA/√Hz
Other Input Characteristics
Common-Mode Input Impedance 10||5 GΩ||pF
Power Supply Rejection Ratio 100 115 dB
Input Operating Voltage Range 0.05 4.95 V
Reference Input
Input Impedance
Voltage Range
= 2.5 V, G = 1, RL = 10 kΩ, TA = 25°C, unless otherwise noted.
REF
+ V
OSI
4 15 μV
OSI
/G
OSO
Average Temperature Drift TA = −55°C to +125°C 0.01 0.05 μV/°C
15 30 μV
OSO
Average Temperature Drift TA = −55°C to +125°C 0.05 0.5 μV/°C
= −55°C to +125°C 5 nA
A
= −55°C to +125°C 0.5 nA
A
G = 1 0.05 %
G = 2 to 128 0.8 %
G = 1 to 32 3 10 ppm/°C
G = 64 4 20 ppm/°C
G = 128 10 30 ppm/°C
0.2 V to 4.8 V, 2 kΩ load 5 ppm
2
+ (eno/G)2), V
ni
IN+
, V
= 2.5 V
IN−
28 kΩ
−0.2 +5.2 V
Rev. 0 | Page 3 of 20
AD8231-EP
Parameter Test Conditions/Comments Min Typ Max Unit
Dynamic Performance
Bandwidth
G = 1 2.7 MHz
G = 2 2.5 MHz
Gain Bandwidth Product
G = 4 to 128 7 MHz
Slew Rate 1.1 V/μs
Output Characteristics
Output Voltage High RL = 100 kΩ to ground 4.9 4.94 V
R
= 10 kΩ to ground 4.8 4.88 V
L
Output Voltage Low RL = 100 kΩ to 5 V 60 100 mV
R
= 10 kΩ to 5 V 80 200 mV
L
Short-Circuit Current 70 mA
Digital Interface
Input Voltage Low TA = −55°C to +125°C 1.0 V
Input Voltage High TA = −55°C to +125°C 4.0 V
T
Setup Time to CS High
Hold Time after CS High
= −55°C to +125°C 50 ns
A
T
= −55°C to +125°C 20 ns
A
OPERATIONAL AMPLIFIER
Input Characteristics
Offset Voltage, VOS 5 15 μV
Temperature Drift TA = −55°C to +125°C 0.01 0.06 μV/°C
Input Bias Current 250 500 pA
T
= −55°C to +125°C 5 nA
A
Input Offset Current 20 100 pA
T
= −55°C to +125°C 0.5 nA
A
Input Voltage Range 0.05 4.95 V
Open-Loop Gain 100 120 V/mV
Common-Mode Rejection Ratio 100 120 dB
Power Supply Rejection Ratio 100 110 dB
Voltage Noise Density 20 nV/√Hz
Voltage Noise f = 0.1 Hz to 10 Hz 0.4 μV p-p
Dynamic Performance
Gain Bandwidth Product 1 MHz
Slew Rate 0.5 V/μs
Output Characteristics
Output Voltage High RL = 100 kΩ to ground 4.9 4.96 V
R
= 10 kΩ to ground 4.8 4.92 V
L
Output Voltage Low RL = 100 kΩ to 5 V 60 100 mV
R
= 10 kΩ to 5 V 80 200 mV
L
Short-Circuit Current 70 mA
BOTH AMPLIFIERS
Power Supply
Quiescent Current 4 5 mA
Quiescent Current (Shutdown) 0.01 1 μA
Rev. 0 | Page 4 of 20
AD8231-EP
VS = 3.0 V, V
Table 3.
Parameter Conditions Min Typ Max Unit
INSTRUMENTATION AMPLIFIER
Offset Voltage VOS RTI = V
Average Temperature Drift 0.01 0.05 μV/°C
Average Temperature Drift 0.05 0.5 μV/°C
Input Currents
Input Bias Current 250 500 pA
T
Input Offset Current 20 100 pA
T
Gains 1, 2, 4, 8, 16, 32, 64, or 128
Gain Error
Gain Drift TA = −55°C to +125°C
CMRR
G = 1 80 dB
G = 2 86 dB
G = 4 92 dB
G = 8 98 dB
G = 16 104 dB
G = 32 110 dB
G = 64 110 dB
G = 128 110 dB
Noise
Input Voltage Noise, eni f = 1 kHz 40 nV/√Hz
f = 1 kHz, TA = −55°C 35 nV/√Hz
f = 1 kHz, TA = 125°C 48 nV/√Hz
f = 0.1 Hz to 10 Hz 0.8 μV p-p
Output Voltage Noise, eno f = 1 kHz 72 nV/√Hz
f = 1 kHz, TA = −55°C 62 nV/√Hz
f = 1 kHz, TA = 125°C 83 nV/√Hz
f = 0.1 Hz to 10 Hz 1.4 μV p-p
Current Noise f = 10 Hz 20 fA/√Hz
Other Input Characteristics
Common-Mode Input Impedance 10||5 GΩ||pF
Power Supply Rejection Ratio 100 115 dB
Input Operating Voltage Range 0.05 2.95 V
Reference Input
Input Impedance
Voltage Range
= 1.5 V, TA = 25°C, G = 1, RL = 10 kΩ, unless otherwise noted.
REF
+ V
/G
OSO
Input Offset, V
Output Offset, V
OSI
4 15 μV
OSI
15 30 μV
OSO
= −55°C to +125°C 5 nA
A
= −55°C to +125°C 0.5 nA
A
G = 1 0.05 %
G = 2 to 128 0.8 %
G = 1 to 32 3 10 ppm/°C
G = 64 4 20 ppm/°C
G = 128 10 30 ppm/°C
e
n
V
IN+
= √(e
, V
IN−
2
+ (eno/G)2)
ni
= 2.5 V, TA = 25°C
28 kΩ||pF
−0.2 +3.2 V
Rev. 0 | Page 5 of 20
AD8231-EP
Parameter Conditions Min Typ Max Unit
Dynamic Performance
Bandwidth
G = 1 2.7 MHz
G = 2 2.5 MHz
Gain Bandwidth Product
G = 4 to 128 7 MHz
Slew Rate 1.1 V/μs
Output Characteristics
Output Voltage High RL = 100 kΩ to ground 2.9 2.94 V
R
Output Voltage Low RL = 100 kΩ to 3 V 60 100 mV
R
Short-Circuit Current 40 mA
Digital Interface
Input Voltage Low TA = −55°C to +125°C 0.7 V
Input Voltage High TA = −55°C to +125°C 2.3 V
Setup Time to CS High
Hold Time after CS High
OPERATIONAL AMPLIFIERS
Input Characteristics
Offset Voltage, VOS 5 15 μV
Temperature Drift TA = −55°C to +125°C 0.01 0.06 μV/°C
Input Bias Current 250 500 pA
T
Input Offset Current 20 100 pA
T
Input Voltage Range 0.05 2.95 V
Open-Loop Gain 100 120 V/mV
Common-Mode Rejection Ratio 100 120 dB
Power Supply Rejection Ratio 100 110 dB
Voltage Noise Density 27 nV/√Hz
Voltage Noise f = 0.1 Hz to 10 Hz 0.6 μV p-p
Dynamic Performance
Gain Bandwidth Product 1 MHz
Slew Rate 0.5 V/μs
Output Characteristics
Output Voltage High RL = 100 kΩ to ground 2.9 2.96 V
R
Output Voltage Low RL = 100 kΩ to 3 V 60 100 mV
R
Short-Circuit Current 40 mA
BOTH AMPLIFIERS
Power Supply
Quiescent Current 3.5 4.5 mA
Quiescent Current (Shutdown) 0.01 1 μA
= 10 kΩ to ground 2.8 2.88 V
L
= 10 kΩ to 3 V 80 200 mV
L
T
= −55°C to +125°C 60 ns
A
T
= −55°C to +125°C 20 ns
A
= −55°C to +125°C 5 nA
A
= −55°C to +125°C 0.5 nA
A
= 10 kΩ to ground 2.8 2.82 V
L
= 10 kΩ to 3 V 80 200 mV
L
Rev. 0 | Page 6 of 20
AD8231-EP
ABSOLUTE MAXIMUM RATINGS
Table 4.
Parameter Rating
Supply Voltage 6 V
Output Short-Circuit Current Indefinite1
Input Voltage (Common-Mode) −VS − 0.3 V to +VS + 0.3 V
Differential Input Voltage −VS − 0.3 V to +VS + 0.3 V
Storage Temperature Range –65°C to +150°C
Operational Temperature Range –55°C to +125°C
Package Glass Transition Temperature 130°C
ESD (Human Body Model) 1.5 kV
ESD (Charged Device Model) 1.5 kV
ESD (Machine Model) 0.2 kV
1
For junction temperatures between 105°C and 130°C, short-circuit operation
beyond 1000 hours can impact part reliability.
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
Table 5.
Thermal Pad θJA Unit
Soldered to Board 54 °C/W
Not Soldered to Board 96 °C/W
The θJA values in Tabl e 5 assume a 4-layer JEDEC standard
board. If the thermal pad is soldered to the board, it is
also assumed it is connected to a plane. θ
at the exposed pad
JC
is 6.3°C/W.
MAXIMUM POWER DISSIPATION
The maximum safe power dissipation for the AD8231-EP is
limited by the associated rise in junction temperature (T
the die. At approximately 130°C, which is the glass transition
temperature, the plastic changes its properties. Even
temporarily exceeding this temperature limit may change the
stresses that the package exerts on the die, permanently shifting
the parametric performance of the amplifiers. Exceeding a
temperature of 130°C for an extended period can result in a loss
of functionality.
) on
J
ESD CAUTION
Rev. 0 | Page 7 of 20
AD8231-EP
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
A1
A2
CS
A0
14
13
15
16
PIN 1
1NC
2–INA (IN-AMP –IN)
AD8231-EP
3+INA (IN-AMP +IN)
(Not to Scale)
4NC
INDICAT OR
TOP VIEW
5
6
SDN
+INB
12 +V
11 –V
10 OUTA (IN-AMP OUT)
9REF
8
7
–INB
S
S
NOTES
1. NC = NO CO NNECT. DO NO T CONNECT T O THIS P IN.
2. THE EX POSED PAD CAN BE CO NNECTED TO THE
NEGATIVE SUPPLY (–V
OUTB (OP AMP OUT)
) OR LEFT FLOATING.
S
09707-002
Figure 2. Pin Configuration
Table 6. Pin Function Descriptions
Pin Number Mnemonic Description
1 NC No Connect. Do not connect to this pin.
2 −INA (IN-AMP −IN) Instrumentation Amplifier Negative Input.
3 +INA (IN-AMP +IN) Instrumentation Amplifier Positive Input.
4 NC No Connect. Do not connect to this pin.
5
SDN
Shutdown.
6 +INB Operational Amplifier Positive Input.
7 −INB Operational Amplifier Negative Input.
8 OUTB (OP AMP OUT) Operational Amplifier Output.
9 REF
Instrumentation Amplifier Reference Pin. It should be driven with a low impedance. Output is
referred to this pin.
10 OUTA (IN-AMP OUT) Instrumentation Amplifier Output.
11 −VS Negative Power Supply. Connect to ground in single-supply applications.
12 +VS Positive Power Supply.
13
CS
Chip Select. Enables digital logic interface.
14 A0 Gain Setting Bit (LSB).
15 A1 Gain Setting Bit.
16 A2 Gain Setting Bit (MSB).
EPAD Exposed Pad. Can be connected to the negative supply (−VS) or left floating.
Rev. 0 | Page 8 of 20
AD8231-EP
TYPICAL PERFORMANCE CHARACTERISTICS
INSTRUMENTATION AMPLIFIER PERFORMANCE CURVES
1000
800
600
HITS
400
200
N: 5956
MEAN: 0.977167
SD: 11.8177
1400
1200
1000
800
HITS
600
400
200
N: 5956
MEAN: –48.0779
SD: 21.0433
0
–100 –80 –60 –40 –20 0 20 40 60 80 100
CMRR (µV/ V)
Figure 3. Instrumentation Amplifier CMR Distribution, G = 1
800
N: 5956
MEAN: 2.06788
700
SD: 1.07546
600
500
400
HITS
300
200
100
0
–15 –10 –5 0 5 10 15
V
(µV)
OSI
Figure 4. Instrumentation Amplifier Input Offset Voltage Distribution
800
N: 5956
MEAN: 10.3901
700
SD: 3.9553
600
500
0
–500 –400 –300 –200 –100 0 100 200 300 400 500
09707-100
GAIN ERROR (µV/V)
09707-103
Figure 6. Instrumentation Amplifier Gain Distribution, G = 1
1400
1200
1000
800
600
INPUT OFFSET (nV)
400
200
0
–55 –45 –35 –25 –15 –5 155 253545556575
09707-101
TEMPERATURE (°C)
09707-207
Figure 7. Instrumentation Amplifier Input Offset Voltage Drift,
−55°C to +125°C
20
15
10
400
HITS
300
200
100
0
–30 –20 –10 0 10 20 30
V
(µV)
OSO
Figure 5. Instrumentation Amplifier Output Offset Voltage Distribution
09707-102
Rev. 0 | Page 9 of 20
5
0
OUTPUT OFFSET (µV)
–5
–10
–55 –45 –35 –25 –15 –5 155 253545556575
TEMPERAT URE (°C)
Figure 8. Instrumentation Amplifier Output Offset Drift, −55°C to +125°C
09707-208
AD8231-EP
2000
1500
V
= MIDSUPPLY
REF
V
= MIDSUPPLY
CM
6
0V, 4.96V
5
1000
500
BIAS CURRENT (pA)
0
–500
–55 –40 –25 –10 5 20 35 50 65 80 95 110 125
3V
5V
TEMPERATURE ( °C)
Figure 9. Instrumentation Amplifier Bias Current vs. Temperature
2.0
1.5
1.0
0.5
0
–0.5
BIAS CURRENT (nA)
–1.0
–1.5
–2.0
–2.5 2.52.01.51.00.50–0.5–1.0–1.5–2.0
VCM (V)
+VS = +2.5V
–V
= –2.5V
S
V
= 0V
REF
Figure 10. Instrumentation Amplifier Bias Current vs.
Common-Mode Voltage, 5 V
1.0
0.8
0.6
0.4
0.2
0
–0.2
BIAS CURRENT (nA)
–0.4
–0.6
–0.8
–1.0
–1.5 1.51.20.90.60.30–0.3–0.6–0.9–1.2
VCM (V)
+VS = +1.5V
–V
= –1.5V
S
V
= 0V
REF
Figure 11. Instrumentation Amplifier Bias Current vs.
Common-Mode Voltage, 3 V
4
3
2
1
INPUT COMMON-MODE VOLT AGE (V)
0
09707-209
5V SINGLE SUPPLY
0V, 2.96V
3V SINGLE SUPPLY
0V, 0.04V
0654321
2.92V, 1.5V
OUTPUT VOLTAGE (V)
4.92V, 2.5V
09707-003
Figure 12. Instrumentation Amplifier Input Common-Mode Range vs.
Output Voltage, V
6
5
0.02V, 4.22V
4
3
0.02V, 2.22V
2
1
0.02V, 0.78V
INPUT COMMON-MODE VOLTAG E (V)
0
054.54.03.53.02.52.01.51.00.5
09707-006
1.5V, 4.96V
5V SINGLE SUPPLY
1.5V, 2.96V
2.98V, 2.22V
3V SINGLE SUPPLY
2.98V, 0.78V
1.5V, 0.04V
OUTPUT VOLTAGE (V)
REF
= 0 V
4.98V, 3.22V
4.98V, 1.78V
.0
09707-004
Figure 13. Instrumentation Amplifier Input Common-Mode Range vs.
SUPPLY
= 1.5 V
REF
2.98V, 2.72V
2.98V, 0.28V
= 2.5 V
REF
4.98V, 3.72V
4.98V,1.28V
.0
09707-005
Output Voltage, V
6
5
4
0.02V, 3.72V
3
2
0.02V, 1.72V
1
INPUT COMMON-MODE VOLTAG E (V)
0.02V, 1.28V
0
054.54.03.53.02.52.01.51.00.5
09707-007
Figure 14. Instrumentation Amplifier Input Common-Mode Range vs.
2.5V, 4.96V
5V SINGLE SUPPLY
2.5V, 2.96V
3V SINGLE
2.5V, 0.04V
OUTPUT VOLTAGE (V)
Output Voltage, V
Rev. 0 | Page 10 of 20
AD8231-EP
50
40
30
20
10
0
GAIN (dB)
–10
–20
–30
–40
100 10M1M100k10k1k
G = 128
G = 64
G = 32
G = 16
G = 8
G = 4
G = 2
G = 1
FREQUENCY (Hz)
Figure 15. Instrumentation Amplifier Gain vs. Frequency
1000
800
900
600
200
0
–200
GAIN ERROR (µV/V)
–400
–600
–800
–1000
G = 1
G = 128
–55 –40 –25 –10 5 20 35 50 65 80 95 110 125
TEMPERATURE ( °C)
Figure 16. Instrumentation Amplifier Gain Drift vs. Temperature
140
G = 128
120
G = 8
100
G = 1
CMRR (dB)
80
60
09707-009
09707-216
20
15
10
–5
–10
CMRR (µV/V)
–15
–20
–25
–30
G = 1
5
G = 8
0
–55 –40 –25 –10 5 20 35 50 65 80 95 110 125
TEMPERATURE ( °C)
G = 128
Figure 18. Instrumentation Amplifier CMRR vs. Temperature
140
120
100
POSITIVE PSRR (dB)
80
60
40
20
0
1 100k10k1k10010
FREQUENCY (Hz )
G = 1
G = 8
G = 128
Figure 19. Instrumentation Amplifier Positive PSRR vs. Frequency
140
120
100
80
60
NEGATIVE PSRR (dB)
40
20
G = 1
G = 8
G = 128
09707-218
09707-146
40
10 100 1k 10k 100k
FREQUENCY (Hz)
Figure 17. Instrumentation Amplifier CMRR vs. Frequency
09707-010
Rev. 0 | Page 11 of 20
0
1 100k100k1k10010
FREQUENCY (Hz )
Figure 20. Instrumentation Amplifier Negative PSRR vs. Frequency
09707-147
AD8231-EP
100
G = +128, 0.4µV/DIV
G = +1, 1µV/DIV
1s/DIV
09707-012
Figure 21. Instrumentation Amplifier 0.1 Hz to 10 Hz Noise
100
G = +1
G = +8
90
G = +128
80
70
60
50
40
NOISE (nV/ Hz)
30
20
10
0
1 10 100 1k
FREQUENCY (Hz)
Figure 22. Instrumentation Amplifier Voltage Noise Spectral Density vs.
Frequency, 5 V, 1 Hz to 1000 Hz
1000
NOISE (nV/ Hz)
G = +1
G = +8
900
G = +128
800
700
600
500
400
300
200
100
0
1 10 100 1k 10k 100k
FREQUENCY (Hz)
Figure 23. Instrumentation Amplifier Voltage Noise Spectral Density vs.
Frequency, 5 V, 1 Hz to 1 MHz
10
1
0.1
CURRENT NOISE (pA/ Hz)
0.01
1 100 k10k1k10010
FREQUENCY (Hz )
09707-107
Figure 24. Instrumentation Amplifier Current Noise Spectral Density
5µs/DIV20mV/DIV
09707-011
09707-013
Figure 25. Instrumentation Amplifier Small Signal Pulse Response, G = 1,
R
= 2 kΩ, CL = 500 pF
L
500pF
300pF
NO
LOAD
09707-008
800pF
4µs/DIV20mV/DIV
09707-014
Figure 26. Instrumentation Amplifier Small Signal Pulse Response for Various
Capacitive Loads, G = 1
Rev. 0 | Page 12 of 20
AD8231-EP
G = +8
G = +32
G = +128
2V/DIV
17.6µs TO 0.01%
21.4µs TO 0.001%
10µs/DIV20mV/DIV
09707-015
Figure 27. Instrumentation Amplifier Small Signal Pulse Response, G = 4, 16,
and 128, R
2V/DIV
= 2 kΩ, CL = 500 pF
L
3.95µs TO 0.01%
4µs TO 0.001%
10µs/DIV0.001%/DIV
09707-016
Figure 28. Instrumentation Amplifier Large Signal Pulse Response,
G = 1, V
= 5 V
S
2V/DIV
100µs/DIV0. 001%/DIV
09707-018
Figure 30. Instrumentation Amplifier Large Signal Pulse Response,
= 5 V
S
0.001%
GAIN (V/V)
0.01%
25
20
15
10
SETTLING TIME (µs)
5
0
1110010
G = 128, V
Figure 31. Instrumentation Amplifier Settling Time vs.
Gain for a 4 V p-p Step, V
25
20
15
= 5 V
S
0.001%
0.01%
k
09707-019
3.75µs TO 0.01%
3.8µs TO 0.001%
10µs/DIV0.001%/DIV
09707-017
Figure 29. Instrumentation Amplifier Large Signal Pulse Response,
G = 8, V
= 5 V
S
Rev. 0 | Page 13 of 20
10
SETTLING TIME (µs)
5
0
1110010
GAIN (V/V)
Figure 32. Instrumentation Amplifier Settling Time vs.
Gain for a 2 V p-p Step, V
= 3 V
S
k
09707-020
AD8231-EP
V
V
+
S
–0.2
–0.4
–0.6
–0.8
–1.0
+1.0
+0.8
SUPPLY VOLTAGES (V)
+0.6
+0.4
+0.2
OUTPUT VO LTAGE SWING REF ERRED TO
–V
S
0.1 1 10 100
OUTPUT CURRENT (mA)
Figure 33. Instrumentation Amplifier Output Voltage Swing vs.
Output Current, V
= 3 V
S
+25°C
–55°C
09707-233
+
S
–0.2
–0.4
–0.6
–0.8
–1.0
+1.0
+0.8
SUPPLY VOLTAGES (V)
+0.6
+0.4
+0.2
OUTPUT VO LTAGE SWING REF ERRED TO
–V
S
0.1 1 10 100
OUTPUT CURRENT (mA)
Figure 34. Instrumentation Amplifier Output Voltage Swing vs.
Output Current, VS = 5 V
+25°C
–55°C
09707-234
Rev. 0 | Page 14 of 20
AD8231-EP
–
–
OPERATIONAL AMPLIFIER PERFORMANCE CURVES
100
80
90
–100
NO
LOAD
60
OPEN-LOOP GAIN (dB)
–20
40
20
0
RL = 10kΩ
= 200pF
C
L
10 10M1M100k10k1k100
FREQUENCY (Hz)
76° PHASE
MARGIN
Figure 35. Operational Amplifier Open-Loop Gain and Phase vs.
= 5 V
S
72° PHASE
MARGIN
100
OPEN-LOOP GAIN (dB)
–20
80
60
40
20
0
RL = 10kΩ
= 200pF
C
L
10 10M1M100k10k1k100
Frequency, V
FREQUENCY (Hz)
Figure 36. Operational Amplifier Open-Loop Gain and Phase vs.
Frequency, V
= 3 V
S
–110
–120
–130
–140
–150
90
–100
–110
–120
–130
–140
–150
300pF
800pF
1nF
OPEN-LOOP PHASE SHIFT (Degrees)
09707-021
1.5nF
5µs/DIV20mV/DIV
09707-024
Figure 38. Operational Amplifier Small Signal Response for
Various Capacitive Loads, V
NO
LOAD
OUTPUT VOLTAGE (0.5V/DIV)
OPEN-LOOP PHASE SHIFT (Degrees)
09707-022
1nF║2kΩ
1.5nF║2k Ω
TIME (5µs/DIV)
Figure 39. Operational Amplifier Large Signal Transient Response, V
= 3 V
S
09707-025
= 5 V
S
NO
LOAD
800pF
1nF
2nF
1.5nF
5µs/DIV20mV/DIV
Figure 37. Operational Amplifier Small Signal Response for
Various Capacitive Loads, V
= 5 V
S
09707-023
Rev. 0 | Page 15 of 20
NO
LOAD
1nF║2kΩ
1.5nF║2k Ω
OUTPUT VOLTAGE (0.5V/DIV)
TIME (5µs/DIV)
Figure 40. Operational Amplifier Large Signal Transient Response, V
09707-026
= 3 V
S
AD8231-EP
V
V
1000
900
800
700
600
500
400
300
200
SPECTRAL NOI SE DENSIT Y (nV/ Hz)
100
0
1100k10k1k10010
FREQUENCY (Hz)
Figure 41. Operational Amplifier Voltage Spectral Noise Density vs. Frequency
3.5
VS = ±2.5V
VS = ±1.5V
3.0
2.5
2.0
1.5
1.0
BIAS CURRENT (nA)
0.5
0
–0.5
–55 –40 –25 –10 5 20 35 50 65 80 95 110 125
TEMPERATURE ( °C)
Figure 42. Operational Amplifier Bias Current vs. Temperature
400
300
200
100
V
= ±2.5V
S
0
–100
BIAS CURRENT (pA)
–200
–300
VS = ±1.5V
09707-141
09707-242
+
S
–0.2
–0.4
–0.6
–0.8
–1.0
+1.0
+0.8
SUPPLY VOLTAGES (V)
+0.6
+0.4
+0.2
OUTPUT VOLTAGE SWING REFERRED TO
–V
S
0.1 1 10 100
OUTPUT CURRENT (mA)
Figure 44. Operational Amplifier Output Voltage Swing vs.
Output Current, V
+
S
–0.2
–0.4
–0.6
–0.8
–1.0
+1.0
+0.8
SUPPLY VOLTAGES (V)
+0.6
+0.4
+0.2
OUTPUT VOLTAG E SWING REFERRED T O
–V
S
0.1 1 10 100
OUTPUT CURRENT (mA)
= 3 V
S
Figure 45. Operational Amplifier Output Voltage Swing vs.
–PSRR
= 5 V
S
+PSRR
Output Current, V
140
120
100
80
60
PSRR (dB)
40
20
+25°C
–55°C
+25°C
–55°C
09707-244
09707-245
–400
–3 3210–1–2
VCM (V)
Figure 43. Operational Amplifier Bias Current vs. Common Mode
09707-109
0
1 100k10k1k10010
FREQUENCY (Hz)
Figure 46. Operational Amplifier Power Supply Rejection Ratio
09707-148
Rev. 0 | Page 16 of 20
AD8231-EP
PERFORMANCE CURVES VALID FOR BOTH AMPLIFIERS
7
6
5
SUPPLY CURRENT (mA)
4
3
2
1
0
2.7 5.95.55.14.74.33.93. 53.1
+25°C
–55°C
SUPPLY VOLTAGE (V)
09707-247
Figure 47. Supply Current vs. Supply Voltage
160
140
120
100
CHANNEL SEPARATIO N (dB)
G = 8
80
60
40
20
0
10 100k10k1k100
G = 128
G = 1
SOURCE CHANNEL: O P AMP AT G = 1
FREQUENCY (Hz)
09707-149
Figure 48. Channel Separation vs. Frequency
Rev. 0 | Page 17 of 20
AD8231-EP
OUTLINE DIMENSIONS
PIN 1
INDICATOR
1.00
0.85
0.80
12° MAX
SEATING
PLANE
4.00
BSC SQ
TOP
VIEW
0.80 MAX
0.65 TYP
0.35
0.30
0.25
3.75
BSC SQ
0.20 REF
0.60 MAX
0.65 BSC
0.05 MAX
0.02 NOM
COPLANARIT Y
0.75
0.60
0.50
0.08
0.60 MAX
(BOTTOM VIEW)
16
13
12
9
8
5
1.95 BSC
FOR PROPER CONNECTION OF
THE EXPOSED PAD, REFER TO
THE PIN CO NFIGURATION AND
FUNCTIO N DESCRIPTIONS
SECTION OF THIS DATA SHEET.
PIN 1
INDICATOR
1
2
.
2
1
.
2
9
.
1
4
0.25 MIN
5
S
0
Q
5
COMPLI ANT TO JEDEC STANDARDS MO -220-VGG C
072808-A
Figure 49. 16-Lead Lead Frame Chip Scale Package [LFCSP_VQ]
4 mm × 4 mm Body, Very Thin Quad
(CP-16-4)
Dimensions shown in millimeters
ORDERING GUIDE
Model1 Temperature Range Package Description Package Option
AD8231TCPZ-EP-R7 −55°C to +125°C 16-Lead LFCSP_VQ, 7” Tape and Reel CP-16-4
1
Z = RoHS Compliant Part.
Rev. 0 | Page 18 of 20
AD8231-EP
NOTES
Rev. 0 | Page 19 of 20
AD8231-EP
NOTES
©2011 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D09707-0-5/11(0)
Rev. 0 | Page 20 of 20
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