SBAA551 June   2022 ADS8661 , ADS8665 , ADS8671 , ADS8675 , ADS8681 , ADS8685 , ADS8689 , ADS8691 , ADS8695 , ADS8699 , INA823 , INA826 , LM317L , LM337L , MUX509 , TPS2661 , TPS560430

 

  1.   Abstract
  2.   Trademarks
  3. 1Introduction
  4. 2Circuit Description
    1. 2.1 Input Stage
    2. 2.2 Multiplexer Stage
    3. 2.3 Instrumentation Amplifier
    4. 2.4 Analog-to-Digital Converter
    5. 2.5 Power Supply
  5. 3Results
    1. 3.1 Accuracy and Noise Performance
    2. 3.2 Common-Mode Rejection of Input Signal
    3. 3.3 Input Impedance
    4. 3.4 Settling Time
    5. 3.5 Input Protection
  6. 4Summary
  7. 5References

2.3 Instrumentation Amplifier

The differential output of the multiplexer stage is applied to an instrumentation amplifier. This circuit uses the INA826, which rejects any VCM superimposed to the input signal. A maximum differential signal of ±12.288 V is supported and is not changed by the INA826 (fixed gain = 1 V/V). An alternative option is the INA823 with lower input offset and slightly higher gain error. The single-ended signal at the output of the INA is provided to the ADC.