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TPA3156D2: distorted output waveform

user4616635
Prodigy 165 points

Part Number: TPA3156D2
Other Parts Discussed in Thread: TPA3118D2

Hi staff, 

Could you advise me the reason or any hints of distorted output waveform?

PVCC: around 26V

input: 2kHz sine, L/R same signal

output load: L: LC filter only, R: 4[ohms] load with LC filter 10uH, 0.68uF

 

When output top level become hi, only positive side is distorted at R output:

 

Following bitmap is zoomed from the above:

 

At first, I think the insufficient of PVCC, but the 2nd bitmap shows wrong; PVCC is stable.

And 2nd bitmap also find the simultaneous off-time of OUTP/OUTL:

 

At the same PVCC line, there’s a TPA3118D2 with 4[ohms] load. TPA3118D2’s output is normal, no distortion. Why is there the problem only for TPA3156D2?

  • +1
    TI__Mastermind 23260 points

    Hello,

    Do the two devices have the same gain setting? 

    If you reduce the gain or input signal amplitude to TAS3156D2, does the issue go away? (this is testing if PVDD level is the issue)

    Regards,
    Sydney Northcutt

  • 0 in reply to Sydney Northcutt
    Prodigy 165 points

    Hello Sydney,

    After my post, the distorted waveform disappeared after adjusting PVCC from 27V to 25V. I thought that this issue from partially OVP of high-side output MOSFET around BS** and OUT** termilans of TPA3156D2.

    FYI: The gain settings of TPA3256D2 and TPA3118D2 are the same. If the output level is low, no distorted waveform.

    Sorry for your inconvenience. Thanks

    Regards,

    Yasunori Okutsu