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

3.2 Board Size

Board size is important because a larger board also results in larger copper pour for ground layers to disperse heat while also providing more surface area to diffuse the heat from the surface of the board to the surrounding air. Total board size being larger does not guarantee better thermal performance because it is important to consider other thermal characteristics of the board as well. A board can have a large surface area but also breaks or bottlenecks in the thermal pathing that result in negligible returns on the thermal resistance of the surface area of the board. Additionally, even if a board is large, if all major heat dissipators are all in the same area then the result will be a worse thermal performance.

For best thermal performance:

  • Make the board as large as possible
  • Place the SoC away from the edge of the board
Table 3-3 AM263x EVM Board Size Comparison
Measurement TMDSCNCD263 LP-AM263
Board dimensions 105.76 x 82.81 mm + 6.09 mm length of HSEC 195.58 x 58.42 mm
Approx. Surface area 9,300 mm2 11,400 mm2
Distance from SoC to board edge 13.39 mm 22.89 mm