TIDUDI9A January   2018  – May 2025 ISOM8610

 

  1.   1
  2.   Description
  3.   Resources
  4.   Features
  5.   Applications
  6.   6
  7. 1System Description
    1. 1.1 Key System Specifications
  8. 2System Overview
    1. 2.1 Block Diagram
    2. 2.2 Highlighted Products
      1. 2.2.1 ISO121x
      2. 2.2.2 SN74LV165A
      3. 2.2.3 SN74LVC1GU04
      4. 2.2.4 TVS3300
      5. 2.2.5 ISOM8600
    3. 2.3 System Design Theory
      1. 2.3.1 Digital Input Stage
      2. 2.3.2 Broken Wire Detection
        1. 2.3.2.1 Case 1: Wire Intact and Input State '1'
        2. 2.3.2.2 Case 2: Wire Intact and Input State '0'
        3. 2.3.2.3 Case 3: Broken Wire
      3. 2.3.3 Readout of Digital Outputs
  9. 3Hardware, Software, Testing Requirements, and Test Results
    1. 3.1 Required Hardware and Software
      1. 3.1.1 Hardware
      2. 3.1.2 Software
    2. 3.2 Testing and Results
      1. 3.2.1 Test Setup
      2. 3.2.2 Test Results
        1. 3.2.2.1 Group-Channel Configuration
        2. 3.2.2.2 Single-Channel Configuration
      3. 3.2.3 Conclusion
  10. 4Design Files
    1. 4.1 Schematics
    2. 4.2 Bill of Materials
    3. 4.3 PCB Layout Recommendations
      1. 4.3.1 Layout Prints
    4. 4.4 Altium Project
    5. 4.5 Gerber Files
    6. 4.6 Assembly Drawings
  11. 5Software Files
  12. 6Related Documentation
    1. 6.1 Trademarks
  13. 7About the Author
    1. 7.1 Acknowledgments
  14. 8Revision History

Description

This reference design shows a compact implementation of 16 isolated digital input channels using TI's ISO121x devices. The design works without an isolated supply and supports up to 100-kHz input signals (200-kbit) per channel. The design is split into two groups of eight channels each. A broken wire detection can be executed using only one additional opto-emulator switch ISOM86xx device for each channel or two opto-emulator switches and one additional capacitor for each group. For this functionality, no secondary side supply is needed, which gives a unique benefit to digital input modules using the ISO121x family, compared to regular digital input modules which need an additional isolated power supply on the field input side for broken wire diagnostic.