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TPA3116D2 modulates output

Adam Torma
Mastermind 45780 points

This is the best class-D amp we’ve used and I think high switching-frequency is helping (1.2MHz) but:

  1. When driven at ~90kHz, it modulates (AM) the output by ~9kHz at around -60dB.  This becomes audible in our setup.  I fear this is being produced at the modulation stage which is internal to the chip.  Any recommendations on how to work on this would be appreciated.  (changing the switching frequency did not help)
  2. Distortion was measured at ~2% THD.  It would be nice if it were lower
  3. The power supply rails are too low (26V).  This can be somewhat mitigated by configuring the output stage to be resonant at ~90khz, but this can cause unstable behavior once and a while.

Thank you,

Adam

  • 0
    TI__Guru**** 189401 points

    Hi, Adam,

    Can you share Play Book for this oppty?

    Is the customer using this for a signal frequency of 90 kHz? Our loop is not designed to operate that fast, so I am not surprised the THD is so high.

    The only hooks we have for AM avoidance are to change the switching frequency. They may find that RC snubbers on the outputs could help, or better filtering on the outputs (LC filter).

    We have no experience with resonant converters... Sorry.

    -d2