16 V Rail-to-Rail, Zero-Drift,
Precision Instrumentation Amplifier
AD8230
Rev. B
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FEATURES
Resistor programmable gain range: 10
1
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
matched 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
1
and 1000, users can adjust the output
offset voltage.
CONNECTION DIAGRAM
8
7
6
5
1
2
3
4
–V
S
V
OUT
R
G
V
REF
2
–IN
TOP VIEW
(Not to Scale)
+V
S
V
REF
1
+IN
AD8230
05063-041
Figure 1. 8-Lead SOIC (R-8)
TEMPERATURE (°C)
150–50 –30 –10 10 30 50 70 90 110 130
OFFSET VOLTAGE (µV RTI)
2.0
1.5
1.0
0.5
0
–0.5
–1.0
–1.5
–2.0
05063-001
Figure 2. Relative Offset Voltage vs. Temperature
2
6
1
7
5
8
4
3
AD8230
V
OUT
–5V
+5
TYPE K THERMOCOUPLE
0.1µF
284Ω
34.8kΩ
0.1µF
05063-002
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.
