Zero Drift, Digitally Programmable
Instrumentation Amplifier
AD8231
Data Sheet
NC
–INA
CS
13
A0
14
15
16
Digitally/pin-programmable gain
G = 1, 2, 4, 8, 16, 32, 64, or 128
Specified from −40°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/μs slew rate
Rail-to-rail output
Shutdown/multiplex
Extra op amp
Single-supply range: 3 V to 5 V
Dual-supply range: ±1.5 V to ±2.5 V
Qualified for automotive applications
A1
FUNCTIONAL BLOCK DIAGRAM
A2
FEATURES
12
1
2
LOGIC
11
+VS
–VS
IN-AMP
10
4
9
REF
06586-001
8
OUTB
6
+INB
5
AD8231
SDN
OUTA
OP
AMP
7
NC
3
–INB
+INA
Figure 1.
Table 1. Instrumentation and Difference Amplifiers by
Category
High
Performance
AD8221
AD82201
AD8222
AD82241
APPLICATIONS
Pressure and strain transducers
Thermocouples and RTDs
Programmable instrumentation
Industrial controls
Weigh scales
Automotive controls
1
Low
Cost
AD6231
AD85531
High
Voltage
AD628
AD629
Mil
Grade
AD620
AD621
AD524
AD526
AD624
Low
Power
AD6271
Digital
Gain
AD82311
AD8250
AD8251
AD85551
AD85561
AD85571
Rail-to-rail output.
GENERAL DESCRIPTION
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 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. C
The AD8231 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 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 is specified over the extended industrial temperature range of −40°C to +125°C. It is available in a 4 mm × 4 mm
16-lead LFCSP.
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