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BD mode vs AD mode

Bruce52209
Prodigy 240 points
Other Parts Discussed in Thread: TAS5613, TPA3100D2

I have been using the TAS5613PHD2EVM evaluation card and it has been working great in our application.  I just noticed that it always operates in BD mode.  And it doesn't look like I can test AD mode to see if AD mode would work better in our application.

I have already read about the differences between the modes... and understand the differences in a superficial way (what the wave forms look like and that one is more efficient than the other - as far as filtering the output.  But I have some questions...

1.  Is it possible to operate the TAS5613PHD2EVM evaluation card in AD mode?  The switches don't look like they will let anyone do that, but what I mean is if I do some cuts and jumpers so that I can set the mode pins... would it work?  Or blow up?

2.  Would the output filter components need to be different?

3. Why wasn't AD mode allowed on the TAS5613PHD2EVM card?  Is AD just not as useful or popular anymore?  Or does AD mode have a rarely used application?

Thanks,

Bruce

  • 0
    TI__Mastermind 18510 points

    Bruce, it is possible to operate TAS5613 in AD or BD mode:  000 and 010 are (2xBTL, AD and BD).  PBTL also can use AD or BD.  These are described in the table MODE SELECTION PINS on page 3 of the data sheet.  I imagine you have already read this section.

    BD is the preferred mode, so the EVM does not provide shunts to change modes easily.  (The change between 2xBTL and 1xPBTL maintains BD mode.)  However, you could cut traces and jumper them to change to AD mode.  As long as you avoid damaging the chip with ESD or mechanical stress, this should work, but please be very careful.  Changes like those are somewhat risky.

    You would not have to change the filter components.

    AD mode always requires an LC filter, because otherwise it generates high ripple current in the load, which can degrade efficiency and consume part of the power capacityr of a loudspeaker.  To cover the bases, I have attached the data sheet for TPA3100D2, which includes a comparison of AD and BD modes.  BD mode is preferred because it generates low ripple current in the load, so it does not require an LC filter in all applications.  Of course, for high power supply voltages and long speaker leads, an LC filter is likely to be required for EMC.

    Best regards,

    Steve.

     

    tpa3100d2.pdf
  • 0 in reply to SteveCrump
    Prodigy 240 points

    Thanks for explaining that.

    -Bruce