Datasheet AD8231 (Analog Devices)

Zero Drift, Digitally Programmable Instrumentation Amplifier Data Sheet AD8231 FEATURES FUNCTIONAL BLOCK DIAGRAM Digitally/pin-programmable gain A2 A1 A0 CS G = 1, 2, 4, 8, 16, 32, 64, or 128 16 15 14 13 Specified from −40°C to +125°C 50 nV/°C maximum input offset drift 1 12 NC +VS 10 ppm/°C maximum gain drift LOGIC 2 11 Excellent dc performance –INA –VS 80 dB minimum CMR, G = 1 IN-AMP 3 10 +INA OUTA 15 μV maximum input offset voltage 500 pA maximum bias current 4 9 NC REF 0.7 μV p-p noise (0.1 Hz to 10 Hz) OP AMP Good ac performance AD8231 2.7 MHz bandwidth, G = 1 5 6 7 8 1.1 V/μs slew rate
01
N B B
0
N NB T
6-
Rail-to-rail output SD
58
+I –I OU
06
Shutdown/multiplex
Figure 1.
Extra op amp Table 1. Instrumentation and Difference Amplifiers by Single-supply range: 3 V to 5 V Category Dual-supply range: ±1.5 V to ±2.5 V High Low High Mil Low Digital Qualified for automotive applications Performance Cost Voltage Grade Power Gain
AD8221 AD6231 AD628 AD620 AD6271 AD82311
APPLICATIONS
AD82201 AD85531 AD629 AD621 AD8250 AD8222 AD524 AD8251
Pressure and strain transducers
AD82241 AD526 AD85551
Thermocouples and RTDs
AD624 AD85561
Programmable instrumentation
AD85571
Industrial controls
1 Rail-to-rail output.
Weigh scales Automotive controls GENERAL DESCRIPTION
The AD8231 is a low drift, rail-to-rail, instrumentation amplifier The AD8231 also includes an uncommitted op amp that can be with software-programmable gains of 1, 2, 4, 8, 16, 32, 64, or 128. used for additional gain, differential signal driving, or filtering. The gains are programmed via digital logic or pin strapping. Like the in-amp, the op amp has an auto-zero architecture, rail- to-rail input, and rail-to-rail output. The AD8231 is ideal for applications that require precision performance over a wide temperature range, such as industrial The AD8231 includes a shutdown feature that reduces current temperature sensing and data logging. Because the gain setting to a maximum of 1 μA. In shutdown, both amplifiers also have resistors are internal, maximum gain drift is only 10 ppm/°C for a high output impedance, which allows easy multiplexing of gains of 1 to 32. Because of the auto-zero input stage, maximum multiple amplifiers without additional switches. input offset is 15 μV and maximum input offset drift is just The AD8231 is specified over the extended industrial tempera- 50 nV/°C. CMRR is 80 dB for G = 1, increasing to 110 dB at ture range of −40°C to +125°C. It is available in a 4 mm × 4 mm higher gains. 16-lead LFCSP.
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Document Outline FEATURES APPLICATIONS FUNCTIONAL BLOCK DIAGRAM GENERAL DESCRIPTION TABLE OF CONTENTS REVISION HISTORY SPECIFICATIONS ABSOLUTE MAXIMUM RATINGS THERMAL RESISTANCE MAXIMUM POWER DISSIPATION ESD CAUTION PIN CONFIGURATION AND FUNCTION DESCRIPTIONS TYPICAL PERFORMANCE CHARACTERISTICS INSTRUMENTATION AMPLIFIER PERFORMANCE CURVES OPERATIONAL AMPLIFIER PERFORMANCE CURVES PERFORMANCE CURVES VALID FOR BOTH AMPLIFIERS THEORY OF OPERATION AMPLIFIER ARCHITECTURE GAIN SELECTION REFERENCE TERMINAL LAYOUT Power Supplies Package Considerations Thermal Pad INPUT BIAS CURRENT RETURN PATH INPUT PROTECTION RF INTERFERENCE COMMON-MODE INPUT VOLTAGE RANGE REDUCING NOISE APPLICATIONS INFORMATION DIFFERENTIAL OUTPUT MULTIPLEXING USING THE AD8231 WITH BIPOLAR SUPPLIES SALLEN KEY FILTER OUTLINE DIMENSIONS ORDERING GUIDE AUTOMOTIVE PRODUCTS