ANALOG DEVICES AD8230 Service Manual
16 V Rail-to-Rail, Zero-Drift,
V
www.BDTIC.com/ADI
Precision Instrumentation Amplifier
FEATURES
Resistor programmable gain range: 101 to 1000
Supply voltage range: ±4 V to ±8 V
Rail-to-rail input and output
Maintains performance over −40°C to +125°C
Excellent ac and dc performance
110 dB minimum CMR @ 60 Hz, G = 10 to 1000
10 μV maximum offset voltage (RTI, ±5 V operation)
50 nV/°C maximum offset drift
20 ppm maximum gain nonlinearity
APPLICATIONS
Pressure measurements
Temperature measurements
Strain measurements
Automotive diagnostics
GENERAL DESCRIPTION
The AD8230 is a low drift, differential sampling, precision
instrumentation amplifier. Auto-zeroing reduces offset voltage
drift to less than 50 nV/°C. The AD8230 is well-suited for
thermocouple and bridge transducer applications. The
AD8230’s high CMR of 110 dB (minimum) rejects line noise in
measurements where the sensor is far from the instrumentation.
The 16 V rail-to-rail, common-mode input range is useful for
noisy environments where ground potentials vary by several
volts. Low frequency noise is kept to a minimal 3 μV p-p,
making the AD8230 perfect for applications requiring the
utmost dc precision. Moreover, the AD8230 maintains its high
performance over the extended industrial temperature range of
−40°C to +125°C.
Two external resistors are used to program the gain. By using
ma
tched external resistors, the gain stability of the AD8230 is
much higher than instrumentation amplifiers that use a single
resistor to set the gain. In addition to allowing users to program
the gain between 10
offset voltage.
Rev. B
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.
1
and 1000, users can adjust the output
AD8230
CONNECTION DIAGRAM
1
–V
S
2
+V
S
3
V
1
REF
4
+IN
AD8230
TOP VIEW
(Not to Scale)
Figure 1. 8-Lead SOIC (R-8)
2.0
1.5
1.0
0.5
0
–0.5
–1.0
OFFSET VOLTAGE (µV RTI)
–1.5
–2.0
TEMPERATURE ( °C)
Figure 2. Relative Offset Voltage vs. Temperature
0.1µF
TYPE K THERMO COUPLE
Figure 3. Thermocouple Measurement
The AD8230 is versatile yet simple to use. Its auto-zeroing
topology significantly minimizes the input and output
transients typical of commutating or chopper instrumentation
amplifiers. The AD8230 operates on ±4 V to ±8 V (+8 V to +16 V)
supplies and is available in an 8-lead SOIC.
1
The AD8230 can be programmed for a gain as low as 2, but the maximum
input voltage is limited to approximately 750 mV.
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 ©2004–2007 Analog Devices, Inc. All rights reserved.
+5
4
AD8230
5
3
8
V
OUT
7
R
G
6
V
2
REF
5
–IN
05063-041
–5V
0.1µF
2
1
8
7
6
34.8kΩ
284Ω
05063-001
150–50 –30 –10 10 30 50 70 90 110 130
V
OUT
05063-002
AD8230
www.BDTIC.com/ADI
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications....................................................................................... 1
General Description......................................................................... 1
Connection Diagram .......................................................................1
Revision History ............................................................................... 2
Specifications..................................................................................... 3
Absolute Maximum Ratings............................................................ 5
Thermal Characteristics .............................................................. 5
ESD Caution.................................................................................. 5
Typical Performance Characteristics............................................. 6
Theory of Operation ...................................................................... 11
Setting the Gain .......................................................................... 11
REVISION HISTORY
9/07—Rev. A to Rev. B
Changes to Features and Layout..................................................... 1
Changes to Table 1............................................................................ 3
Changes to Table 2............................................................................ 4
Changes to Layout............................................................................ 5
Inserted Figure 13, Figure 14, and Figure 15; Renumbered
Sequentially ....................................................................................... 7
Changes to Figure 16 and Figure 19............................................... 8
Updated Outline Dimensions....................................................... 15
Level-Shifting the Output ......................................................... 12
Source Impedance and Input Settling Time........................... 12
Input Voltage Range................................................................... 13
Input Protection ......................................................................... 13
Power Supply Bypassing ............................................................ 13
Power Supply Bypassing for Multiple Channel Systems ....... 13
Layout .......................................................................................... 14
Applications ................................................................................ 14
Outline Dimensions ....................................................................... 15
Ordering Guide .......................................................................... 15
7/05—Rev. 0 to Rev. A
C
hanges to Excellent AC and DC Performance............................1
Changes to Table 1.............................................................................3
Changes to Table 2.............................................................................4
Changes to Figure 7 and Figure 8....................................................6
Changes to Figure 10 and Figure 11................................................7
Changes to Level-Shifting the Output Section........................... 11
Changes to Figure 31...................................................................... 11
Inserted Figure 32 and Figure 33; Renumbered Sequentially .. 11
Changes to Source Impedance and Input Settling Time Section,
Input Protection Section and Power Supply Bypassing for
Multiple Channel Systems Section............................................... 12
Changes to Figure 36...................................................................... 13
Changes to Applications Section.................................................. 13
10/04—Revision 0: Initial Version
Rev. B | Page 2 of 16
AD8230
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SPECIFICATIONS
VS = ±5 V, V
Table 1.
Parameter Conditions Min Typ Max Unit
VOLTAGE OFFSET
RTI Offset, V
Offset Drift
COMMON-MODE REJECTION (CMR)
CMR to 60 Hz with 1 kΩ Source Imbalance VCM = −5 V to +5 V 110 120 dB
VOLTAGE OFFSET RTI vs. SUPPLY (PSR)
G = 2 120 120 dB
G = 202 120 140 dB
GAIN G = 2(1 + RF/RG)
Gain Range 10
Gain Error
G = 2 0.01 0.04 %
G = 10 0.01 0.04 %
G = 100 0.01 0.04 %
G = 1000 0.02 0.05 %
Gain Nonlinearity 20 ppm
Gain Drift
G = 2, 10, 102 14 ppm/°C
G = 1002 60 ppm/°C
INPUT
Input Common-Mode Operating Voltage Range −V
Over Temperature T = −40°C to +125°C −V
Input Differential Operating Voltage Range 750 mV
Average Input Offset Current
Average Input Bias Current
OUTPUT
Output Swing −VS + 0.1 +VS − 0.2 V
Over Temperature T = −40°C to +125°C −VS + 0.1 +VS − 0.2 V
Short-Circuit Current 15 mA
REFERENCE INPUT
Voltage Range
NOISE
Voltage Noise Density, 1 kHz, RTI V
Voltage Noise f = 0.1 Hz to 10 Hz 3 μV p-p
SLEW RATE VIN = 500 mV, G = 10 2 V/μs
INTERNAL SAMPLE RATE 6 kHz
POWER SUPPLY
Operating Range (Dual Supplies) ±4 ±8 V
Operating Range (Single Supply) 8 16 V
Quiescent Current T = −40°C to +125°C 2.7 3.5 mA
TEMPERATURE RANGE
Specified Performance −40 +125 °C
1
The AD8230 can operate as low as G = 2. However, since the differential input range is limited to approximately 750 mV, the AD8230 configured at G < 10 does not
make use of the full output voltage range.
2
Gain drift is determined by the TC match of the external gain setting resistors.
3
Differential source resistance less than 10 kΩ does not result in voltage offset due to input bias current or mismatched series resistors.
4
For G < 10, the reference voltage range is limited to −VS + 4.24 V to +VS – 2.75 V.
= 0 V, RF = 100 kΩ, RG = 1 kΩ (@ TA = 25°C, G = 202, RL = 10 kΩ, unless otherwise noted).
REF
V
OSI
2
3
3
4
= V
+IN
V
+IN
T
A
= 0 V 10 μV
−IN
= V
= 0 V,
−IN
50 nV/°C
= −40°C to +125°C
1
S
S
VCM = 0 V 33 300 pA
VCM = 0 V 0.15 1 nA
−VS + 3.5 +VS − 2.5 V
, V
, V
IN+
= 0 V 240 nV/√Hz
IN−
REF
1000 V/V
+V
+V
S
S
V
V
Rev. B | Page 3 of 16
AD8230
www.BDTIC.com/ADI
VS = ±8 V, V
Table 2.
Parameter Conditions Min Typ Max Unit
VOLTAGE OFFSET
RTI Offset, V
Offset Drift
COMMON-MODE REJECTION (CMR)
CMR to 60 Hz with 1 kΩ Source Imbalance VCM = −8 V to +8 V 110 120 dB
VOLTAGE OFFSET RTI vs. SUPPLY (PSR)
G = 2 120 120 dB
G = 202 120 140 dB
GAIN G = 2(1 + RF/RG)
Gain Range 10
Gain Error
G = 2 0.01 0.04 %
G = 10 0.01 0.04 %
G = 100 0.01 0.04 %
G = 1000 0.02 0.05 %
Gain Nonlinearity 20 ppm
Gain Drift
G = 2, 10, 102 14 ppm/°C
G=1002 60 ppm/°C
INPUT
Input Common-Mode Operating Voltage Range −V
Over Temperature T = −40°C to +125°C −V
Input Differential Operating Voltage Range 750 mV
Average Input Offset Current
Average Input Bias Current
OUTPUT
Output Swing −VS + 0.1 +VS − 0.2 V
Over Temperature T = −40°C to +125°C −VS + 0.1 +VS − 0.4 V
Short-Circuit Current 15 mA
REFERENCE INPUT
Voltage Range
NOISE
Voltage Noise Density, 1 kHz, RTI V
Voltage Noise f = 0.1 Hz to 10 Hz 3 μV p-p
SLEW RATE VIN = 500 mV, G = 10 2 V/μs
INTERNAL SAMPLE RATE 6 kHz
POWER SUPPLY
Operating Range (Dual Supplies) ±4 ±8 V
Operating Range (Single Supply) 8 16 V
Quiescent Current T = −40°C to +125°C 3.2 4 mA
TEMPERATURE RANGE
Specified Performance −40 +125 °C
1
The AD8230 can operate as low as G = 2. However, since the differential input range is limited to approximately 750 mV, the AD8230 configured at G < 10 does not
make use of the full output voltage range.
2
Gain drift is determined by the TC match of the external gain setting resistors.
3
Differential source resistance less than 10 kΩ does not result in voltage offset due to input bias current or mismatched series resistors.
4
For G < 10, the reference voltage range is limited to −VS + 4.24 V to +VS − 2.75V.
= 0 V, RF = 100 kΩ, RG = 1 kΩ (@ TA = 25°C, G = 202, RL = 10 kΩ, unless otherwise noted).
REF
V
OSI
= V
+IN
V
+IN
= 0 V 20 μV
−IN
= V
= 0 V,
−IN
50 nV/°C
T = −40°C to +125°C
1
2
3
3
4
S
S
VCM = 0 V 33 300 pA
VCM = 0 V 0.15 1 nA
−VS + 3.5 +VS − 2.5 V
, V
, V
IN+
= 0 V 240 nV/√Hz
IN−
REF
1000 V/V
+V
+V
S
S
V
V
Rev. B | Page 4 of 16
AD8230
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ABSOLUTE MAXIMUM RATINGS
Table 3.
Parameter Rating
Supply Voltage ±8 V, +16 V
Internal Power Dissipation 304 mW
Output Short-Circuit Current 20 mA
Input Voltage (Common-Mode) ±V
Differential Input Voltage ±V
Storage Temperature Range −65°C to +150°C
Operational Temperature Range −40°C to +125°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.
S
S
THERMAL CHARACTERISTICS
Specification is for device in free air SOIC.
Table 4.
Parameter Value Unit
θJA (4-Layer JEDEC Board) 121 °C/W
ESD CAUTION
Rev. B | Page 5 of 16
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