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

6 Summary

A high accuracy bridge amplifier to 4-20-mA current loop transmitter was successfully designed and measured. The final results are summarized in Table 6-1.

Table 6-1 Summary of Key Design Criteria and Results
Design CriteriaResults & Comments
Use XTR references (4.096-V and 5-V) to power sensor and amplifier circuitryDesign only uses XTR reference voltages
Total current consumption < 3.5-mATotal current consumption = 3.39mA
Weight range = 0 to 20-lbs → output current = 4 to 20-mAWeight range = 0 to 20-lbs → output current = 4.0994 to 20.1545-mA. Approximately 0.1-mA offset due to limits of standard resistor values.
±0.1% accuracyDesign is accurate to ±0.1%