AD8231 [ADI]
Zero Drift, Digital Programmable Instrumentation Amplifier; 零漂移，数字可编程仪表放大器
| 型号： | AD8231 |
| 厂家： | 
ADI |
| 描述： | Zero Drift, Digital Programmable Instrumentation Amplifier |
| 文件： | 总8页 (文件大小：137K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
Zero Drift, Digital Programmable
Instrumentation Amplifier
Preliminary Data Sheet
AD8231
FEATURES
Digitally programmable gain
G= 1, 2, 4, 8, 16, 32, 64, 128
Software or pin programmable
Excellent temperature performance
Specified from −40°C to +125°C
50 nV/°C max input offset drift
10 ppm/°C max gain drift
Excellent dc performance
122 dB min CMR, G = 128
25 μV max input offset voltage
100 pA max bias current
SDN
A0
A2
WR
A1
OUT2
-IN
N
P
OUT1
+IN
0.7 uV p-p (0.1 Hz to 10 Hz)
Good ac performance
AD8231
-VS
REF
+VS
Gain Bandwidth Product 1 MHz
Slew Rate 0.7 V/ꢀs
Figure 1. AD8231 Functional Diagram
Rail-to-rail input and output
Shutdown/Multiplex
Additional uncommitted op amp
Supply range: 3.0V to 5.5V
APPLICATIONS
Pressure and Strain Transducers
Thermocouples and RTDs
Programmable Instrumentation
Industrial Controls
Weigh Scales
GENERAL DESCRIPTION
The AD8231 also includes an uncommitted op amp which can
be used for additional gain, differential signal driving or
filtering. Like the in amp, the op amp has an autozero
architecture, rail to rail input, and rail to rail output.
The AD8231 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 includes a shutdown feature that reduces current
to 1 uA and makes the amplifier output high impedance. This
allows easy multiplexing of multiple amplifiers without
additional switches.
The AD8231 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/ºC.
Because of the autozero input stage, maximum input offset is 25
uV and maximum input offset drift is just 50 nV/ºC. CMRR is
also guaranteed over temperature: 80 dB for G=1, increasing to
122 dB at a gain of 128. Voltage noise is just 0.7 uV p-p (0.01
Hz to 10 Hz).
The AD8231 is specified over the extended industrial
temperature range of -40°C to +125°C. It is available in a 4mm
x 4mm 16-Lead LFCSP (Chip Scale) package.
Rev. PrC
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.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
Fax: 781.326.8703
www.analog.com
© 2007 Analog Devices, Inc. All rights reserved.
AD8231
Preliminary Data Sheet
SPECIFICATIONS
Table 1. VS = 5 V, VREF = 2.5 V, G=1, RL = 10 kΩ, -40°C ≤TA ≤ +125°C unless otherwise noted).
Parameter
Conditions
Min
Typ
Max
Unit
INSTRUMENTATION AMPLIFIER
OFFSET VOLTAGE
VOS RTI = VOSI + VOSO/G
Input Offset, VOSI
5
25
μV
Average Temperature Drift
Output Offset, VOSO
Average Temperature Drift
INPUT CURRENTS
0.01
15
0.02
0.05
50
0.1
μV/°C
μV
μV/°C
Input Bias Current
TA = 25°C
200
50
400
1
100
0.5
pA
nA
pA
nA
Input Offset Current
TA = 25°C
GAINS
Gain Error
G = 1
G = 2 to 128
Gain Drift
G = 1
G = 2 to 128
Gain Nonlinearity
G= 1
1, 2, 4, 8, 16, 32, 64, 128
0.1
1
0.3
TBD
%
%
2
2
10
10
ppm/°C
ppm/°C
VOUT = 0.1 to 4.9V
5
TBD
TBD
ppm
ppm
ppm
G= 8
G= 128
CMRR
G=1
G=2
G=4
G=8
G=16
G=32
G=64
G=128
NOISE
80
86
92
98
104
110
116
122
100
106
112
118
124
130
136
142
dB
dB
dB
dB
dB
dB
dB
dB
Noise RTI = sqrt(eni2 + (eno/G)2
VIN+, VIN− =2.5V ; TA = 25°C
f = 1 kHz,
f = 0.1 Hz to 10 Hz
f = 0.01 Hz to 1 Hz
f = 1 kHz
Input Voltage Noise, eni
32
0.7
0.2
60
1
nV/√Hz
μV p-p
μV p-p
nV/√Hz
μV p-p
μV p-p
Output Voltage Noise, eno
f = 0.1 Hz to 10 Hz
f = 0.01 Hz to 1 Hz
0.5
OTHER INPUT CHARACTERISTICS
Differential Input Impedance
Common Mode Input Impedance
Power Supply Rejection Ratio
Input Operating Voltage Range
REFERENCE INPUT
Common Mode
Differential
10||5
10||5
110
GΩ||pF
GΩ||pF
dB
100
0.05
4.95
4.95
V
Input Impedance
Voltage Range
10||10
GΩ||pF
V
0.05
Rev. PrC | Page 2 of 8
Preliminary Data Sheet
AD8231
DYNAMIC PERFORMANCE
Gain Bandwidth Product
Slew Rate
1
0.6
MHz
V/μs
OUTPUT CHARACTERISTICS
Output Voltage High
RL = 100kΩ to ground
RL = 10kΩ to ground
RL = 100kΩ to 5V
4.9
4.8
4.94
4.88
60
80
20
V
V
mV
mV
mA
Output Voltage Low
100
200
RL = 10kΩ to 5V
Short-Circuit Current
DIGITAL INTERFACE
Input Voltage Low
Input Voltage High
Leakage Current
Setup Time : tDS
Hold Time: tDH
Write Width: tCS
Gain switching time
OPERATIONAL AMPLIFIER
INPUT CHARACTERISTICS
Offset Voltage, VOS
Temperature Drift
Input Bias Current
10
1.0
V
V
4.0
TBD
nA
ns
ns
ns
ns
TBD
TBD
TBD
TBD
10
0.01
200
30
μV
uV/°C
pA
nA
pA
nA
V
V/mV
dB
dB
0.05
400
1
100
0.5
4.95
TA = 25°C
TA = 25°C
Input Offset Current
50
Input Voltage Range
Open Loop Gain
Common-Mode Rejection Ratio
Power Supply Rejection Ratio
Voltage Noise Density
Voltage Noise
0.05
TBD
100
100
110
110
17
TBD
TBD
nV/√Hz
μV p-p
f = 0.1 Hz to 10 Hz
0.4
DYNAMIC PERFORMANCE
Gain Bandwidth Product
Slew Rate
1
0.6
MHz
V/μs
OUTPUT CHARACTERISTICS
Output Voltage High
RL = 100kΩ to ground
RL = 10kΩ to ground
RL = 100kΩ to 5V
4.9
4.8
4.96
4.92
60
80
20
V
V
mV
mV
mA
Output Voltage Low
100
200
RL = 10kΩ to 5V
Short-Circuit Current
10
BOTH AMPLIFIERS
POWER SUPPLY
Quiescent Current
3.5
1
TBD
TBD
TBD
4.5
10
mA
uA
ns
ns
GΩ||pF
Quiescent Current (Shutdown)
SHD high to high output impedance
SHD low to low output impedance
Shutdown output impedance
Rev. PrC | Page 3 of 8
AD8231
Preliminary Data Sheet
Table 2. VS = 3.3 V, VREF = 1.65 V, -40°C ≤TA ≤ +125°C, G=1, RL = 10 kΩ, unless otherwise noted).
Parameter
Conditions
Min
Typ
Max
Unit
INSTRUMENTATION AMPLIFIER
OFFSET VOLTAGE
VOS RTI = VOSI + VOSO/G
Input Offset, VOSI
5
25
μV
Average Temperature Drift
Output Offset, VOSO
Average Temperature Drift
INPUT CURRENTS
0.01
15
0.02
0.05
50
0.1
nV/°C
μV
μV/°C
Input Bias Current
TA = 25°C
200
5
400
1
100
0.5
pA
nA
pA
nA
Input Offset Current
TA = 25°C
GAINS
Gain Error
G= 1
G= 2 to 128
Gain Drift
G= 1
G= 2 to 128
Gain Nonlinearity
G= 1
1, 2, 4, 8, 16, 32, 64, 128
0.1
1
0.3
TBD
%
%
2
2
10
10
ppm/°C
0.1 to 3.2V
TBD
TBD
TBD
ppm
ppm
ppm
G= 8
G= 128
CMRR
G=1
G=2
G=4
G=8
G=16
G=32
G=64
G=128
NOISE
80
86
92
98
104
110
116
122
100
106
112
118
124
130
136
142
dB
dB
dB
dB
dB
dB
dB
dB
Noise RTI = sqrt(eni2 + (eno/G)2
VIN+, VIN− =2.5V; TA = 25°C
f = 1 kHz
f = 0.1 Hz to 10 Hz
f = 0.01 Hz to 1 Hz
f = 1 kHz
Input Voltage Noise, eni
45
0.7
0.2
60
1
nV/√Hz
μV p-p
μV p-p
nV/√Hz
μV p-p
μV p-p
Output Voltage Noise, eno
f = 0.1 Hz to 10 Hz
f = 0.01 Hz to 1 Hz
0.5
OTHER INPUT CHARACTERISTICS
Differential Input Impedance
Common Mode Input Impedance
Power Supply Rejection Ratio
Input Operating Voltage Range
REFERENCE INPUT
Common Mode
Differential
10||5
10||5
110
GΩ||pF
GΩ||pF
dB
100
0.05
3.25
3.25
V
Input Impedance
Voltage Range
10||10
GΩ||pF
V
0.05
Rev. PrC | Page 4 of 8
Preliminary Data Sheet
AD8231
DYNAMIC PERFORMANCE
Gain Bandwidth Product
Slew Rate
1
0.6
MHz
V/μs
OUTPUT CHARACTERISTICS
Output Voltage High
RL = 100kΩ to ground
RL = 10kΩ to ground
RL = 100kΩ to 3.3V
RL = 10kΩ to 3.3V
3.2
3.1
3.24
3.18
60
80
20
V
V
mV
mV
mA
Output Voltage Low
100
200
Short-Circuit Current
DIGITAL INTERFACE
Input Voltage Low
Input Voltage High
Leakage Current
Setup Time : tDS
Hold Time: tDH
Write Width: tCS
Gain switching time
OPERATIONAL AMPLIFIER
INPUT CHARACTERISTICS
Offset Voltage, VOS
Temperature Drift
Input Bias Current
10
0.7
V
V
2.0
TBD
nA
ns
ns
ns
ns
TBD
TBD
TBD
TBD
10
0.01
200
30
μV
uV/°C
pA
nA
pA
nA
V
V/mV
dB
dB
0.05
400
1
100
0.5
3.25
TA = 25°C
TA = 25°C
Input Offset Current
50
Input Voltage Range
Open Loop Gain
Common-Mode Rejection Ratio
Power Supply Rejection Ratio
Voltage Noise Density
Voltage Noise
0.05
TBD
100
100
110
110
25
TBD
TBD
nV/√Hz
μV p-p
f = 0.1 Hz to 10 Hz
0.4
DYNAMIC PERFORMANCE
Gain Bandwidth Product
Slew Rate
1
0.6
MHz
V/μs
OUTPUT CHARACTERISTICS
Output Voltage High
RL = 100kΩ to ground
RL = 10kΩ to ground
RL = 100kΩ to 3.3V
RL = 10kΩ to 3.3V
3.2
3.1
3.26
3.12
60
80
20
V
V
mV
mV
mA
Output Voltage Low
100
200
Short-Circuit Current
10
BOTH AMPLIFIERS
POWER SUPPLY
Quiescent Current
3
1
TBD
TBD
TBD
4
10
mA
uA
ns
ns
GΩ||pF
Quiescent Current (Shutdown)
SHD high to high output impedance
SHD low to low output impedance
Shutdown output impedance
Rev. PrC | Page 5 of 8
AD8231
Preliminary Data Sheet
ABSOLUTE MAXIMUM RATINGS
Table 2. AD8231 Absolute Maximum Ratings
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 may affect device reliability.
Parameter
Rating
Supply Voltage
Internal Power Dissipation
Output Short Circuit Current
Input Voltage (Common-Mode)
Differential Input Voltage
Storage Temperature
–65°C to +150°C
Operational Temperature Range –40°C to +125°C
A2 A1 A0 WR
16 15 14 13
1
12 +Vs
NC
(In-Amp -IN) -INA
(In-Amp +IN) +INA
NC
11 GND
2
3
4
AD8231
10
9
OUTA (In-Amp Out)
REF
Top View
5
6
7
8
SDN +INB -INB OUTB (Op Amp Out)
16-Lead LFCSP (Chip Scale) Package
Pin Number
Mnemonic
Function
Pin Number
Mnemonic
Function
1
NC
No connect
9
REF
Reference Pin to set the
Output Level
2
3
-INA
Negative Input for In-
amp
10
11
OUTA
GND
Output for In Amp
+INA
Positive Input for In-
amp
Power Supply Ground
4
5
NC
No connect
Shut Down
12
13
+Vs
WR
Positive Power Supply
SDN
Write Enable to latch
gain setting
6
7
8
+INB
-INB
Positive Input for
Undedicated Op Amp
14
15
16
A0
A1
A2
Gain Setting Bit
Gain Setting Bit
Gain Setting Bit
Negative Input for
Undedicated Op Amp
OUTB
Output for
Undedicated Op Amp
Rev. PrC | Page 6 of 8
Preliminary Data Sheet
AD8231
GAIN SELECTION
The AD8231’s gain is set by voltages applied to the A0, A1, and
A2 pins. High (HI) or low (LO) voltage limits are listed in the
WR
specifications section. To change the gain, the
pin must be
WR
driven low. When the
pin is driven high, the gain is
latched, and voltages at the A0-A2 pins will have no effect. Table
3 is the truth table showing the different gain settings.
A2 A1 A0 Gain
WR
LO
LO
LO
LO
LO
LO
LO
LO
HI
LO LO LO
LO LO HI
LO HI LO
LO HI HI
1
2
4
8
HI LO LO 16
HI LO HI 32
HI HI LO 64
HI HI HI 128
X
X
X
No change
Table 3 Truth table for AD8231’s gain settings
Rev. PrC | Page 7 of 8
AD8231
Preliminary Data Sheet
ESD CAUTION
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily
accumulate on the human body and test equipment and can discharge without detection. Although
this product features proprietary ESD protection circuitry, permanent damage may occur on devices
subjected to high energy electrostatic discharges. Therefore, proper ESD precautions are
recommended to avoid performance degradation or loss of functionality.
Rev. PrC | Page 8 of 8
PR06586-0-1/07(PrC)
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