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TLV320AIC3262 Mini-DSP instruction map cleared

Other Parts Discussed in Thread: TLV320AIC3262

We are using the Mini-DSP in the AIC3262 codec. We have noticed that after powering on/off the DAC a number of times we lose the sound. When checking the DAC Mini-DSP Instruction map we could see that it been partly cleared (set to zero). We get this effect just by powering on/off the DAC. More and more addresses in the instruction map is set to zero and after a while the Mini-DSP stops working.

What could be the problem?

Regards Bjorn Qvarnstrom

  • Hi Bjorn,

    Can you specify and example of a book, page and registers that get cleared? I would like to ensure that you are referring to I-RAM and not C-RAM.

    I-RAM should remain intact as long as DVDD and IOVDD are present.

    Regards,
    J-
  • Hi

    Thanks for your answer.

    The registers that get cleared differs between runs. One example is book 120, page 1, register 32. When running on/off many times more registers get cleared on different pages.

    Regards

    Bjorn

  • Hi Bjorn,

    I'm suspecting power supply glitches. Can you double check the power supply and also that the decoupling for IOVDD and DVDD is proper?

    Thanks!
    J-
  • Thanks for the answer,
    Hi and thanks for the answers

    We have done some measuring to check for power glitches, but nothing abnormal is showing on the scope. To debug the power supply further we tried connecting DVDD (1.8V) and AVDD(3.3V) to a external power cube. This solved the problem. The problems also disappears if the speaker is disconnected.

    So it looks like there is a problem with the power supply, but why can't we see it, any ideas?

    We have also noticed that we get quite loud pops from the speaker when it is powered up, like there is a DC component. There is no de-pop function for the Class-D amplifier, so what can be done to minimize these pops?

    Regards
    Bjorn
  • Bjorn,

    If speakers are disconnected and issue is resolved this leads me to believe that high current spikes are causing issues with the power supply. Please check the decoupling caps (e.g. are they close to the pins, proper value, etc) and also if power supply is capable of delivering the peak currents that it needs to deliver power to the load.

    The Class-D is a differential output so there will be an offset of SPVDD/2 at each pin, but between +/- terminals there should be 0VDC. The scripts provided in the TLV320AIC3262 Application Reference Guide should provide the best pop performance. Note that the writing sequence is important.

    Regards,
    J-