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TPA3255: Some question need to help for test

user5883945
Expert 2026 points
Part Number: TPA3255


Dear,

   Customer have some question after test, the test result shows as word attachment.

TPA3255 test.docx

  • 0
    TI__Mastermind 20541 points

    hi,

    usually for audio circuit, we only consider the signal <20kHz for human ear cannot hear signal over 20kHz.

    usually, we test THD use AES17(20kHz) which filter out the signal over 20kHz.

    no need to use the other filter to filter the AC harmonics at 450kHz.

    it would be better to use Audio Precision to test the THD for your output to see whether any problem exist.

    tks

    jesse

  • 0
    TI__Expert 5810 points

    Hi 

    About your questions:

    Question 1: If the nominal harmonic index needs to be reached, additional filtering circuit is needed to filter the AC harmonics of 450kHz/900mVpp.

    Yes, the results tested in the datasheet use the AP's filter. The purpose is to filter out the harmonic more than 20kHz.

    Question 2: I If a filter circuit is really needed, is there a reasonable filter circuit recommended for resistive loads (such as increasing inductance for T-type filtering, or multistage LC filtering)?

    You can take below links as a reference.

    AUX-0025 / 0040 / 0100 Switching Amplifier Measurement Filters - Audio Precision (ap.com)

    We recommend using AP to do the test.

    BR.

    Wei Qiu.