Instrumentation amplifier combines power efficiency, zero-drift accuracy for portable devices - Embedded.com

Instrumentation amplifier combines power efficiency, zero-drift accuracy for portable devices

The AD8237 micro-power, zero-drift precision instrumentation amplifier from Analog Devices, Inc. offers a power-efficient solution for precision signal and sensor conditioning at a competitive price. The AD8237 features a low input offset drift (< 0.3µV/ºC) and an industry leading input signal range that extends 300 mV beyond the supply rails. Combined with a maximum gain error and drift of 0.005% and 0.5 ppm/°C respectively, and CMRR (common-mode rejection ratio) of 114 dB, the device offers precision measurement even at low gain. With a low quiescent supply current of just over 100 µA, the amplifier is well suited for signal conditioning bridge, temperature and other similar sensors used in low-power designs. Target applications for the AD8237 include portable and battery-powered healthcare, consumer, and precision instrumentation equipment such as infusion pumps, mobile blood pressure monitors, 4- to 20-mA sensors, gaming peripherals, and consumer weigh scales.

The AD8237 operates off a single supply voltage of 1.8 V to 5.5 V and ships in a compact MSOP-8 package. The gain (1 to 1000) is set by the ratio of two external resistors, which combined with industry leading gain error performance, provides superior gain accuracy over temperature.

Summary of key features

  • Gain Range: 1 to 1000
  • CMRR: 114 dB
  • DC Precision
  • Input offset voltage: 75 µV
  • Offset drift: 0.3 µV/°C
  • Supply Current: 115 µA
  • Supply Range: 1.8V to 5.5V
  • Bandwidth (G=100): 10 kHz
  • Gain Error: 0.005%
  • Gain Drift: 0.5ppm/°C
  • Input Voltage Noise: 1.5 uVp-p

The AD8237 operates well in a system with a variety of SAR A/D converters such as the AD7988-1 ultralow power 16-bit SAR converter.

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