SBAA631 January   2025 DAC80508 , INA592 , XTR111 , XTR300 , XTR305

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2Analog Output Module Specification
  6. 3Analog Output Module Structure
  7. 4Multi-Channel Output Architectures
    1. 4.1 Fully Integrated DAC Architecture
    2. 4.2 Low Voltage DAC Plus an Output Buffer
    3. 4.3 Track and Hold Multiplexed Output
  8. 5Single-Channel Output Architectures
    1. 5.1 Fully Integrated DAC
    2. 5.2 Low-Voltage DAC Plus an Output Buffer
    3. 5.3 Pulse-Width Modulation Plus a Buffer
  9. 6Output Buffers
    1. 6.1 Unidirectional Current Buffer
    2. 6.2 Bidirectional Current Buffer
    3. 6.3 Voltage Buffer
    4. 6.4 Combined Voltage or Current Buffer
  10. 7Summary
  11. 8References

3 Analog Output Module Structure

The Figure 3-1 application page on TI.com provides a rich source of information about TI designs for PLC analog output. The page supports the generic structure of the AOUT module as shown in the following figure.

Analog Output Module StructureFigure 3-1 Analog Output Module Structure

The core of the AOUT module front-end is a digital-to-analog DAC converter, which drives output buffers either voltage or current. DAC requires a voltage reference, and HART modem is optional for current outputs. Power for AOUT front-end either comes from the field side, or less common from the backplane over isolated stage. This is a functional diagram, the different functions can either be integrated into one device or spread over multiple devices.

This article focuses on the front-end architectures, and what can be the correct architecture to use based on different requirements.