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

3.5 Relative Position of Heat Emitters

The AM263x device is not the only package that is dissipating heat on a PCB. It is important to make a conscious effort to separate all heat-releasing components or else the thermal resistance between the board and ambient temperature will suffer as a result. Examples of components that run warmer include but are not limited to:

  • Other processors or microcontrollers
  • Power Management Integrated Chips (PMIC)
  • Voltage regulators
  • LIN and Ethernet PHY

For best thermal performance:

  • Ensure that there is sufficient distance between known heat emitters on the PCB.

Figure 3-3 shows how the LaunchPad was designed to separate low-dropout (LDO) voltage regulator's heat radiation from the AM263x device. The AM263x Control Card is designed with a heat-emitting package near the SoC but the package is responsible for supplying the 25 MHz clock to the SoC. In this instance, the signal integrity of the operating clock is more important than impacting thermal resistance. Because the control card follows other thermal design rules listed in this document, it is easy to overlook the potential impact of one heat-emitting package near the SoC. Figure 3-4 shows the thermal camera view of the AM263x Control Card.

Note: The following images are taken with a thermal camera where the AM263x device was running a max power use-case and the boards soaked at an ambient temperature of 25°C for 15 minutes.
GUID-E73D9A3E-5EAF-488E-B05E-124DFA0C5F3D-low.png Figure 3-3 LP-AM263x Thermal Camera
GUID-5F8C6D63-2594-419B-9495-C2A3851C133E-low.png Figure 3-4 TMDS263CNCD Thermal Camera