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TAS5822M: Power limitation

Part Number: TAS5822M

Tool/software:

Dears,

  Is there a way to limit the maximum power, regardless of how many ohms the speaker is

  • Hi,

    I will reach out to the team and update you with an answer early next week. In the meantime, please refer to this matrix.

    Regards,

    Sam

  • Dears,

    Let me repeat the customer's needs:
    At 8 ohms, the power is limited to 25W using DRC, but after using 4 ohms, the power will exceed and cause power overload.
    The customer needs a way to ensure that the power does not exceed the set limit, regardless of whether the load is 8 ohms or 4 ohms. thanks!

  • hi 

    base on power calculation formula, power is calculated base on resistor value.

    amplifier is a kind of voltage amplify device, if without detecting resistor function, amp cannot output the corresponding power.

    so, the only way is you need to calculate the voltage your 2 load can suffer and pick the smallest one as the amp max output voltage so that output power do not exceed what you expect.

    tks

    jesse

  • Hi ,

     Customer found a new issue, DRC is set to 8 Ω, with a power limit of 25W. The speaker uses 4 Ω, but when the volume is adjusted to a power of only 7W, an error occurs. The IC heats up severely, the system is protected, and the speaker is silent.

  • hi,

    can customer share the schematic ?

    also, about the inductor Isat, have customer select proper value base on the "inductor section" in the datasheet?

    and, about the gain setting, have customer use above formula to do a calculation?

    tks

    jesse

  • Hi

    The compressed file of the attachment contains the customer's inductance datasheet 10uH, schematic , and PCB PDF, which helps to check how to improve efficiency and heat dissipation.

    TAS5822M.rar

  • hi

    there seems no special problem with customer's sch and pcb.

    DRC is set to 8 Ω

    about the DRC setting, it should be -xx dB, can you tell me how they do the calculation.

    base on customer's setting, 25w/4ohm -> Urms = 10vrms. Upeak = 10*sqrt(2) = 14.4v.

    pvdd = 24v. so the digital gain should be applied to -4.4v. AG should be applied to -1.8v.

    with proper gain setting to make sure output power not exceed 25w.

    tks

    jesse

  • Hi,

    DRC settings refer to the formulas in the table above.
    The current problem is that when using a 4 Ω speaker with a power of 7W, the IC heats up severely, causing protection to be activated and the amplifier to be turned off. After verification using the EVM board, the 4 Ω amplifier can achieve a power of over 30W.
    The customer believes that it is not a DRC issue, but rather a IC efficiency and heat problem.

  • Hi 

    Even if the DRC function is turned off, there is still this problem. Is there any improvement method that can accept changing the PCB board.

  • hi,

    usually, there should be no this problem.

    please confirm below several points:

    1.have you really confirmed customer's output waveform whether it is really as what they said output is 7w.

    if no, please let customer share the output waveform. also, the pvdd value, waveform before LC filter, after LC fitler.

    2.what confirming DRC threshold value is to confirm the setting is correct or not, this help us understand does customer setting correct.

    3.there might having chip issue, have customer change to other chip to double confirm? this is only 1 chip issue or all chips having same problem.

    4.cusotmer can also use the thermal gun to confirm which component generating the most heat lead ? this can also help finding out what might be the heat source.

    tks

    jesse