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

2.2 Package Defined Thermal Resistance Characteristics

GUID-4DBAF36A-8C49-47DA-957D-0F48BA9032A8-low.png Figure 2-2 Thermal Resistances of a System

RΘJA is dependent on many factors and some of these thermal resistance characteristics are constant across system designs. Figure 2-2 shows the various thermal resistances in a system. The constant characteristics are defined by the ability for heat to dissipate from the die to the external parts of the package case. The thermal resistance between the junction and the board is defined by RΘJB and the thermal resistance between the junction and case (lid) is defined by RΘJC. The lid of the package also has a thermal resistance between the lid and the ambient temperature or RΘCA. Since the AM263x only has one package type, RΘJC and RΘJB are constant. RΘCA can be lowered by applying air flow over the lid.

Figure 2-3 shows the circuit representation of high-level thermal resistances, whether or not they vary between designs.

Note: In order to lower the junction temperature of the System on a chip (SoC), system design choices must be made to help with the thermal dissipation of the PCB or air flow must be introduced to help with the board/case to ambient thermal resistance. For more information on the board defined thermal resistances, refer to Section 2.3.
GUID-0E34E939-72EF-408A-B313-C45A7DECB036-low.png Figure 2-3 Basic Thermal Resistances of a system