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

5.3 AM263x EVM Comparison

The two EVMs that were used to observe junction temperature in relation to ambient temperature are the AM263x Control Card and AM263x LaunchPad. These two systems have different qualities and design choices that affect the thermal performance of the AM263x SoC. Table 5-1 details the relevant differences in PCB design.

Table 5-1 AM263x EVM Comparison
Measurement TMDSCNCD263 LP-AM263
Number of thermal vias 90 90
Drill hole diameter 8 mil 8 mil
Plating thickness 35 um 20-30 um
Conductively filled vias Resin filled Empty cavity
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
Ground layer copper thickness 1.26 mil 1.26 mil
Copper weight 1 oz/sq ft 1 oz/sq ft
Total number of layers 10 6
Number of ground layers 4 2

Based on the comparison table, it can be theorized that the thermal performance of the AM263x Control Card will be better than the AM263x LaunchPad. Despite the Launchpad having a slightly larger surface area, the Control Card features four ground layers for improved heat dispersion. Designing the PCB with twice as many ground layers should have a very apparent impact on the relationship between junction temperature and ambient temperature.