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TPA3255: THD curve of TPA3255 is different from actual & datasheets.

downey KIM
Intellectual 600 points
Part Number: TPA3255

Hello.

TI team.

my customer is reviewing the TPA3255EVM. THD spec of TPA3255 is different from actual & datasheets.

measurement condition.

Equipment : AP515, AP525 / AUX0025
PVDD : 51V

Load : 8ohm

digital filter : 20Hz Butterworth HPF, 80kHz Butterworth LPF, A weight


1. analog input : 0.24V
output : 2.8V (1W)

THD : 0.03%

2. analog input : 1.2V
output : 14.356V (25W)
THD : 0.29%


3. analog input : 2V
output : 24V (100W)
THD : 0.3%

Actual measurement THD curve (25W, 8ohm)

Request point.

1. Do you have TPA3255EVM test data? if you have that, please send to me.

2. Let me know measurement condition for THD curve of TPA3255 datasheet . (value & part No of LC filter, test equipment model No, ... etc)

3. Why THD spec of TPA3255 is different from actual & datasheets? What did we set wrong?

Thanks and regards

Downey kim.

  • 0
    TI__Mastermind 27990 points
    Hi Downey,

    1. The EVM test data closely replicates the data sheet numbers.

    2. The test conditions are always stated at the top of the data sheet plots. For most of the testing, 10 uH inductor and 1 uF capacitor was used with a 20 kHz AES17 filter was used for testing. This was done on an AP2722.

    3. There are a few configuration choices available on the EVM depending on if you are doing SE, BTL, or PBTL output. Have you checked with the EVM users guide that you have the EVM configured for the correct input and output configuration you are using?

    Justin
  • 0
    Guru 140200 points
    Hi Downey,

    the photo shows that the EVM has electrical contact to the metal enclosure directly underneath. I would isolate the spacing bolts from this metal enclosure.

    What about your heatsink temperature? Does cooling the heatsink improve the THD data?

    Kai
  • 0 in reply to kai klaas69
    Intellectual 600 points

    Hi Kai,

    THD performance of EVM is the same regardless of location. and because the test time is short, the heat sink temperature is very low.

    I don`t know why THD performance is low.

    EVM is BTL mode. (2ch stereo)

    Downey.

  • 0 in reply to downey KIM
    TI__Mastermind 27990 points
    Hi Downey,

    Have you done a loop back with the AP to make sure it can pass through the AUX filter without issue? I would then look at the FFT/SNR measurement to look at the noise floor. The noise floor should be around 85 uVrms with A weighting on the EVM. If these look alright, i would look at the output configuration of the AP, and the jumper settings for the input of the EVM.

    if you are using the J10 and J12 inputs, you will want to use the "diff" setting on J4 and J19. Are you using the RCA inputs to the EVM or the J10 and J12 differential inputs?

    Justin
  • 0 in reply to Justin Bohr
    TI__Mastermind 27990 points
    Hi Downey,

    Since there has not been any response on this thread I will assume that you have solved the issue and I will be closing the thread.

    Justin