SLLS552G December   2002  – September 2022 SN65HVD20 , SN65HVD21 , SN65HVD22 , SN65HVD23 , SN65HVD24

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Description (continued)
  6. 6 Device Comparison
  7. 7 Pin Configuration and Functions
  8. 8 Specifications
    1. 8.1  Absolute Maximum Ratings
    2. 8.2  ESD Ratings
    3. 8.3  Recommended Operating Conditions
    4. 8.4  Thermal Information
    5. 8.5  Driver Electrical Characteristics
    6. 8.6  Receiver Electrical Characteristics
    7. 8.7  Driver Switching Characteristics
    8. 8.8  Receiver Switching Characteristics
    9. 8.9  Receiver Equalization Characteristics
    10. 8.10 Power Dissipation
    11. 8.11 Typical Characteristics
  9. 9 Parameter Measurement Information
  10. 10Detailed Description
    1. 10.1 Overview
    2. 10.2 Functional Block Diagram
    3. 10.3 Feature Description
    4. 10.4 Device Functional Modes
      1. 10.4.1 Test Mode Driver Disable
      2. 10.4.2 Equivalent Input and Output Schematic Diagrams
  11. 11Application and Implementation
    1. 11.1 Application Information
    2. 11.2 Typical Application
      1. 11.2.1 Design Requirements
      2. 11.2.2 Detailed Design Procedure
        1. 11.2.2.1 Noise Considerations for Equalized Receivers
      3. 11.2.3 Application Curves
  12. 12Power Supply Recommendations
  13. 13Layout
    1. 13.1 Layout Guidelines
    2. 13.2 Layout Example
  14. 14Device and Documentation Support
    1. 14.1 Receiving Notification of Documentation Updates
    2. 14.2 Support Resources
    3. 14.3 Trademarks
    4. 14.4 Electrostatic Discharge Caution
    5. 14.5 Glossary
  15. 15Mechanical, Packaging, and Orderable Information

13.1 Layout Guidelines

In addition to the guidelines on differential trace matching given in Section 11.2.2, the layout guidelines below must be followed:

  • Route power and ground nets as planes rather than traces, and keep their widths as large as possible to minimize resistance and inductance while maximizing parasitic capacitance.
  • If external components (like transient voltage suppression diodes) are used for transient protection, place them close to the connector port and within the path of the signal lines. Make sure component capacitances are small enough not to impact the RS-485 signaling at the chosen data rate.
  • Small-valued series pulse-proof resistances can be used to provide additional immunity to transients. This is needed to limit input currents if the clamping voltages of external transient protection devices exceed the absolute maximum ratings of the transceiver. These resistances must be less than 10 Ω so that the RS-485 signal is not overly attenuated.