AD8231:  Zero Drift, Digitally Programmable Instrumentation Amplifier

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.

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, rail-to-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 tempera-ture range of −40°C to +125°C. It is available in a 4 mm × 4 mm 16-lead LFCSP.

• Pressure and strain transducers
• Thermocouples and RTDs
• Programmable instrumentation
• Industrial controls
• Weigh scales