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TAS6424E-Q1: Heatsink @ 24V PVDD

Raphael Knoop
Prodigy 60 points

Part Number: TAS6424E-Q1
Other Parts Discussed in Thread: TAS6424E, TAS6424-Q1, TAS6424

Hi,

I am currently designing a 4 channel amplifier board with the TAS6424E. Each channel should provide 50W in BTL @ 4Ohms configuration, therefore I have to run it at 24V PVDD according to the datasheet. But which thermal resistance of the heatsink is then required. From figure 7-8 I can read that power dissipation will be @ ~9W but this is at 14.4V PVDD. So what will be the power dissipation at 24V?

Raphael

  • 0
    TI__Mastermind 45035 points

    Hi Raphael,

    The heatsink requirement depends on your average power that needs to be dissipated.  The thermal resistance does not change with power supply voltage.  It is a fixed value determined by the package thermal characteristics.  You can use the datasheet for the TAS6424-Q1 device for this data.  The X-axis is power for all 4 channels combined.

  • 0 in reply to Gregg Scott
    Prodigy 60 points

    Hi Gregg,

    thank you for your reply but it confuses me a bit. It is clear that thermal resistance does not change with supply voltage. Actually the question is, what is the power dissipation of the device if I ask 50W per channel from it running the device at 24V PVDD. I cannot find the information in the data sheets neither in TAS6424 nor in TAS6424E.

    Now you said that the X-axis is power for all 4 channels combined. That opens two new questions:

    Can I not run all four channels at the rated max. power at the same time because this will result in OTP?

    In the data sheet of the TAS6424E there is an example calculation for proper heat sink selection. But the value for dissipated power does not match the diagrams in the data sheet. Even not with you latest info that all 4 channels are combined. What am I missing here?

    Raphael

  • +1 in reply to Raphael Knoop
    TI__Mastermind 45035 points

    Hi Raphael,

    Let me break this apart a bit for clarity.

    1. The thermal requirements depend on your average power over time.  Then the average power dissipation can be determined
    2. The power dissipation at 4 x 50W continuously is outside the realistic use case of typical audio signals.  Typical average power is less than 50% of max power for very loud signals and less than 30% of max power for normal to loud signals.  It can be run at full power with the appropriate heatsink and thermal interface material at room temperature.  There is a high potential for OTP when driven continuously at high power.
    3. Use Figure 34 in the TAS6424-Q1 datasheet for power dissipation.
    4. The datasheet for TAS6424E is still "Advanced Information" and will be updated when the device is formally released.

    Regards
    Gregg Scott

  • 0 in reply to Gregg Scott
    Prodigy 60 points

    Gregg, thank you, that makes it clear.