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TPA3244EVM: PFFB parameters

Jeffrey
Expert 1920 points
Part Number: TPA3244EVM
Other Parts Discussed in Thread: TPA3244

Dear All,

My customer is designing PFFB(Post Filter Feedback) application of TPA3244 like bellow picture 1.

They designed PFFB parameters like bellow picture 2, but there was a fault error and no output.

So they need the recommended PFFB component values and parameters like bellow picture 2.

Their conditions are as follows.

Input voltage and current : 24V(PVDD), 5A

Output power : 40W stereo(BTL)

Speaker impedance : 6ohm

Please let me know that.

1. PFFB application (picture 1)

2. Recommended PFFB component values and parameters (picture 2)

Regards

Jeffrey

  • 0
    TI__Genius 9670 points
    Hi Jeffrey,

    Are they using the EVM or their own board? You may look at the startup of the input signal and output PWM to see if their is a feedback issue at startup.

    Thanks,
    Brian
  • 0 in reply to Brian Burk
    Expert 1920 points
    Hi Brian,

    They are using the EVM of TPA3244.
    They applied the recommended PFFB component values except R_in(2.7kohm) on EVM like above picture 2.
    They changed R_in value from 2.7kohm to 820ohm because of resolving a fault error issue.
    Is it ok? or Is there any recommended value of R_in or other component values?

    Test results (original EVM vs. EVM with PFFB circuit) are as follows.
    They think that there is not a big effect on this PFFB circuit like SLAA788 application report.
    1. S/N
    Original EVM : 108.6dB @RL=6ohm, Po=36W, PVDD=24V, BTL
    EVM with PFFB circuit : 110.8dB @RL=6ohm, Po=35W, PVDD=24V, BTL
    2. THD+N
    Original EVM : 0.0036% @Po=1W
    EVM with PFFB circuit : 0.0033% @Po=1W

    Regards
    Jeffrey
  • 0 in reply to Jeffrey
    TI__Mastermind 24835 points
    Hi Jeffery,
    Pleae let us know if this issue is resolved. Please help to close it if it's resolved.
  • 0 in reply to Shawn Zheng
    Expert 1920 points
    Hi Shawn,

    I'm waiting for the answer from Brian Burk.
    But I didn't get that and this issue hasn't been resolved yet.
    Can you recommend or comment on this issue?

    Regards
    Jeffrey
  • 0 in reply to Jeffrey
    TI__Mastermind 24835 points
    Hi Jeffrey,
    I'm sorry for that. Justin will get back to you later.
  • 0 in reply to Shawn Zheng
    TI__Mastermind 27920 points
    Hi Jeffrey,

    Sorry for the delay. Changing the Rin value will of course change the overall behavior of the design. We don't have mush information of test results other than the circuit we have provided, so any tweaks to the circuit will need to be verified.

    In terms of performance, using a different set of values than what we have tested with can certainly produce different results in terms of performance and stability. I would recommend going back to the recommended 2.7 kkOhm resistor for Rin if you would like the stated performance. Of course then the fault issue would need to be debugged.

    Otherwise, the amplifier/board may be limited performance wise by the environment. I would take a look at the power supply noise first, as it seems your starting SNR was also higher than our reference EVM.

    Justin
  • 0 in reply to Justin Bohr
    Expert 1920 points
    Hi Justin,

    Thanks for your reply and advice.
    I'll check that.

    Regards
    Jeffrey