SDAA162 July   2026 ADS125H18 , ISO7721 , ISO7730 , ISO7731 , SN6505B , SN74LVC1G17 , TUSB320 , TVS3301

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Design Overview and Measurement Performance (Normal Operation)
    1. 1.1 Design Overview
    2. 1.2 EMC Test Board Voltage Measurement Performance During Normal Operation
    3. 1.3 EMC Test Board Current Measurement Performance During Normal Operation
  5. 2EMC Test Board Circuit and PCB Layout Considerations
    1. 2.1 Circuit Design Considerations for EMC Compliance
      1. 2.1.1 High-Voltage Capacitors and Resistors on Every Input Connector Pin
      2. 2.1.2 TVS Diodes
      3. 2.1.3 Protecting the Current Shunt: PTC and Zener Diodes
      4. 2.1.4 Series Resistors on Digital Signals
      5. 2.1.5 Digital Isolation
      6. 2.1.6 Power Supply and Protection
      7. 2.1.7 High-Voltage Capacitors and Resistors for Discharging Path
    2. 2.2 PCB Layout Considerations for EMC Compliance
      1. 2.2.1 PCB Layer Stack-up and Ground Plane
      2. 2.2.2 Avoiding a Long Return Path
      3. 2.2.3 Avoiding 90-Degree Bends in PCB Traces
      4. 2.2.4 Using a Guard Ring to Isolate Interference Signals
      5. 2.2.5 Decoupling Capacitors
      6. 2.2.6 Differential Signal Routing
      7. 2.2.7 Stitching Vias
      8. 2.2.8 Layout for Isolation Barrier
      9. 2.2.9 Component Placement
  6. 3EMC Test System, Standards, and Results
    1. 3.1 EMC Test System
    2. 3.2 EMC Test Standards
    3. 3.3 EMC Test Results
      1. 3.3.1 Electrostatic Discharge (ESD)
      2. 3.3.2 Radiated Immunity (RI)
      3. 3.3.3 Electrical Fast Transients (EFT)
      4. 3.3.4 Surge Immunity (SI)
      5. 3.3.5 Conducted Immunity (CI)
  7. 4Schematic, PCB Layout and Bill of Materials
    1. 4.1 Schematic
    2. 4.2 PCB Layout
    3. 4.3 Bill of Materials (BOM)
  8. 5Summary
  9. 6References

2.1 Circuit Design Considerations for EMC Compliance

This section describes the EMC test board circuit design that protects the ADS125H18, improves system EMC performance, and maintains measurement accuracy. Figure 2-1 shows a block diagram of the ADS125H18 EMC test board:

ADS125H18 EMC Test Circuit Board with 10V Input Signal and PHI ConnectionFigure 2-1 ADS125H18 EMC Test Circuit Board with 10V Input Signal and PHI Connection

Considerations for the EMC test board include: