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TPA3251: Sync'ing devices - when is it necessary?

Supira Medical
Intellectual 300 points
Part Number: TPA3251

Tool/software:

Hi,

In an application where I have only two TPA3251 devices for a total of four BTL channels, is it necessary to sync the oscillators? These will run off the same power supply but will have lower power demands (midrange and tweeter).

Thanks!

  • 0
    TI__Genius 9195 points

    Hi Supira,

    You do not need to sync the devices if you do not wish to do so. Syncing the devices can allow for less stress on the power supply and allow for better performance as outlined in this app note, but is not necessary for design. My recommendation would be to have some un-populated 0 ohm resistors in place so you can switch to syncing the devices if you prefer. This would mean routing the OSC pins through unpopulated 0 ohms resistors, and have the freq_adj pin for one of the devices have an option to tie to DVDD instead of a resistor to ground.

    Regards,

    Ramsey

  • 0 in reply to Ramsey Foote
    Intellectual 300 points

    Hi Ramsey,

    That's exactly how I have things designed at the moment but was hoping to get a "feel" for how much of a performance loss there might be if not sync'ed.

    A related question - from a PCB layout standpoint, I assume it's not a good idea to have the IOM and IOP lines cross the analog input lines, even if done at right angles?

    Thanks.

  • 0 in reply to Supira Medical
    TI__Genius 9195 points

    Hi Supira,

    The IOP and IOM signals are not that fast (on the order of hundreds of kHz) so a crossing would be ok if done at 90 degrees. That being said, no crossing would be better unless it makes other parts of the layout worse.

    Regards,

    Ramsey

  • 0 in reply to Ramsey Foote
    Intellectual 300 points

    Thanks Ramsey. I figured out a way to avoid crossing the lines altogether.

    As always, your assistance is much appreciated.