SBOA594 August   2024 OPA2990

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1 Introduction
  5. 2 Circuit Description
  6. 3 Supporting Multiple Output Ranges
  7. 4 Resistor Sizing, M2 Selection, and Other Design Considerations
  8. 5 Mode and Range Control
  9. 6 Supply Level for Current Output
  10. 7 Supply Levels for Voltage Output
  11. 8 Protection Features
  12. 9 Measurement Results
  13. 10Power Consumption
  14. 11Error Monte-Carlo Analysis
  15. 12Rise and Fall Times
  16. 13Building Multi-Channel Output
  17. 14Summary
  18. 15References

1 Introduction

PLC analog control signals of actuators are typically 4-to 20mA or ±10V. the same is true for 4 and 3-wire Sensor transmitters. A common practice is to use low voltage DACs (3.3V or 5V powered) to drive an output stage (with power > ±10V). The ability to drive either voltage or current on the same output terminals adds desired flexibility to the PLC output module or the sensor transmitter.

This article explores the efficient construction of a combined voltage and current output stage using an opamp with a shutdown feature. Also discussed is the methods to protect the stage against over voltage and over current, as well as the expected performance of such a stage. Additionally, the process of building multi-channel modules using this output stage is shared.