SPRADB7 September   2023 AM2431 , AM2432 , AM2434 , AM2631 , AM2631-Q1 , AM2632 , AM2632-Q1 , AM2634 , AM2634-Q1 , AM263P4-Q1 , AM2732 , AM2732-Q1

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
    1. 1.1 How to Use This Application Note
    2. 1.2 Glossary
  5. 2Thermal Resistance Overview
    1. 2.1 Junction Vs. Ambient Temperature
    2. 2.2 Package Defined Thermal Resistance Characteristics
    3. 2.3 Board Defined Thermal Resistances
  6. 3Board Design Choices that Affect Thermal Performance
    1. 3.1 Thermal Vias
    2. 3.2 Board Size
    3. 3.3 Air Flow, Heat Sinking, and Enclosures
    4. 3.4 Copper Thickness
    5. 3.5 Relative Position of Heat Emitters
    6. 3.6 Layer Count
    7. 3.7 Breaks in Thermal Pathing
  7. 4Thermal Design Best Practices Review
  8. 5AM263x EVM Thermal Comparison with Data
    1. 5.1 Test Setup and Materials
    2. 5.2 Measurement Logging Software
    3. 5.3 AM263x EVM Comparison
    4. 5.4 Measurement Results
      1. 5.4.1 Lid Temperature Readings
      2. 5.4.2 Power Readings over Temperature
      3. 5.4.3 Calculated Thermal Resistance Values
      4. 5.4.4 Recorded Junction and Ambient Temperatures
      5. 5.4.5 Calculated Junction Temperature at Ambient Temperature Extremes
  9. 6Using the Thermal Model
  10. 7References

4 Thermal Design Best Practices Review

The following list can be reviewed to review whether a board design is following the basic rules for optimizing the thermal dissipation of the SoC. This list captures the rules of thumb that are in each board design choice subsection from Section 3

Note: For worst-case thermal scenarios, all system design details need to be taken into account, including enclosure characteristics and presence of air flow.

For best thermal performance:

  • Thermal Vias
    • Use vias on each VSS pin of the BGA.
    • Use the widest possible traces from the BGA to the via in a dogbone fanout.
    • Use the largest possible drill diameter.
    • Use conductively filled thermal vias.
  • Board Size
    • Make the board as large as possible.
    • Place the SoC away from the edge of the board.
  • Air Flow and Heat Sinking
    • Use an enclosure that is optimized for thermal performance.
    • Include fans in the enclosure design.
    • Use a heat sink attached to the BGA Case lid.
    • Maintain consistent air flow to the system.
  • Copper Thickness
    • Maximize the area of each copper layer.
    • Use heavier copper layers.
  • Relative Position of Heat Emitters
    • Ensure that there is sufficient distance between known heat emitters on the PCB.
  • Layer Count
    • Increase the total number of layers.
    • Increase the number of ground layer copper pours.
  • Breaks in Thermal Pathing
    • Review each ground layer and ensure there are no copper pour cutouts that impede heat flow.