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

1.1 How to Use This Application Note

Many factors can influence the junction temperature of a device. Therefore, it is important to understand what PCB design choices impact thermal resistance and subsequently junction temperature.

  • Chapter 3: Thermal Resistance Overview
    • The thermal resistance overview explains all of the thermal resistances to consider in a system and how the thermal resistance between junction and ambient temperature is heavily influenced by PCB design.
  • Chapter 4: Board Design Choices that Affect Thermal Performance
    • There are many factors to consider when designing a PCB. This chapter details how certain factors affect the ability for heat to dissipate away from the device and lower junction temperature. The design choices for two different AM263x EVMs are detailed for each of the factors and best practices are included in each section.
  • Chapter 5: Thermal Design Best Practices Review
    • This chapter combines all of the best practices for each design factor into a single page for quick and easy review.
  • Chapter 6: AM263x EVM Thermal Comparison with Data
    • A testing script was developed to measure the junction temperature across an ambient temperature sweep with two different AM263x EVMs. The results detail how the PCB design differences between the two EVMs impacted the thermal resistance between junction and ambient temperature. Operating power and thermal resistance were also recorded across the ambient temperature sweep.
  • SoC Power Estimation Tool
    • Each Sitara MCU has an associated Power Estimation Tool (PET) under the Design tools & simulation section of the device product page. The PET is used to approximate the power consumption for the device under the operating conditions of the designed system.
  • Chapter 7: Using the Thermal Model
    • When a PCB design is complete, then the best practice is to import the design and any enclosure into a thermal simulation software. The PET output provides an estimation of the power consumption that can be used to produce a more realistic thermal model of the system. The simulations can calculate junction temperature for a given system and environment parameters by using the SoC thermal model. The device thermal model can be found under the Design tools & simulation section of the device product page.

GUID-EF2A2B04-342D-4EDC-BCC4-F0F6E4EEBF1C-low.png Figure 1-1 Application Note Chapter Flow