SBOA575 September   2023 INA823 , OPA2387 , XTR115 , XTR116

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2Theory of Operation
    1. 2.1 Wheatstone Bridge Sensor
    2. 2.2 2-Amp INA
    3. 2.3 4-20-mA Current Loop Transmitter Interface
  6. 3Simulation
  7. 4PCB Design
  8. 5Verification and Measured Performance
  9. 6Summary
  10. 7Reference
  11.   Appendix

Abstract

This application note proposes a field transmitter design using a precision voltage amplifier to condition the output of a Wheatstone bridge sensor. This document also shows how the voltage output of the amplifier can be translated into a 4-20-mA signal with a current loop transmitter. All sensor and amplifier circuitry are powered by the current loop transmitter. Additionally, this application note covers the selection of the amplifier and passive components to achieve the required gain and voltage-to-current conversion. Error sources, PCB layout considerations, and measured results are also discussed.