SLAA996A June   2021  – June 2021 TPA6304-Q1

 

  1.   Trademarks
  2. 1Introduction
  3. 2Understanding the Thermal Flow
  4. 3Understanding the Test and System Conditions
    1. 3.1 Device Efficiency
    2. 3.2 Test Signals
      1. 3.2.1 Sinusoidal Signal
      2. 3.2.2 Pink Noise
      3. 3.2.3 Music File
    3. 3.3 Ambient Temperature
    4. 3.4 Junction Temperature
    5. 3.5 Thermal Interface Material and Heatsink
  5. 4Calculating Dynamic Thermal Dissipation
  6. 5Designing a Realistic Thermal Test
  7. 6Thermal Tests
    1. 6.1 Test Setup
    2. 6.2 5W 1kHz Sine Wave Test
      1. 6.2.1 Calculations
      2. 6.2.2 Dynamic Calculation Results
      3. 6.2.3 Tested Results
      4. 6.2.4 Summary of Results
    3. 6.3 10W 1kHz Sine Wave Test
      1. 6.3.1 Calculations
      2. 6.3.2 Dynamic Calculation Results
      3. 6.3.3 Tested Results
      4. 6.3.4 Summary of Results
    4. 6.4 5W Pink Noise Test
      1. 6.4.1 Calculations
      2. 6.4.2 Dynamic Calculation Results
      3. 6.4.3 Tested Results
      4. 6.4.4 Summary of Results
    5. 6.5 10W 1kHz 85°C Test
      1. 6.5.1 Calculations
      2. 6.5.2 Dynamic Calculation Results
      3. 6.5.3 Tested Results
      4. 6.5.4 Summary of Results
  8. 7Overall Summary
  9. 8References
  10. 9Revision History

5 Designing a Realistic Thermal Test

When determining how to design a thermal test, the first thing to consider is how most users will use the device. In most situations the end user will run music and voice signals through the audio amplifiers. Music and voice audio signals are not at a single continuous power level, these signals are dynamically changing. Creating a realistic and challenging thermal test, should be designed not for continuous peak power but rather the expected average power, or slightly above it. For most audio systems in cars, this average output power per channel is between 4W to 10W into a 4Ω speaker.

Looking for θCA with 4W per channel, 4Ω loads, the total power dissipation in the TPA6304-Q1 will be about 5.19W. Assuming the junction temperature and ambient temperature is 130°C and 75°C, respectively:

θCA = (130 - 75)/5.19 - 0.6 = 10°C/W

Now to find θCA for the same conditions except for 10W per channel and 9W of power dissipated:

θCA = (130 - 75)/9 - 0.6 = 5.5°C/W

The maximum allowed thermal resistance of the thermal dissipation material nearly doubles when going from 10W per channel to 4W per channel. Designing for 10W per channel continuous output power will require a more thermally conductive solution than one used for the 4W per channel.