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TMS320F28377S: Dead band while pwm sync happens

Jordan Zhou
Genius 9810 points
Part Number: TMS320F28377S

Hi,

Customer would like to know, what's the worst case for dead band, when pwm sync happens.

It could be that, during dead band active, an external sync comes.

Thanks a lot.

Br, Jordan

  • 0
    TI__Guru 52020 points
    So you would like to know what happens if we are in the deadband region of a pwm period cycle, then a sync occurs. would it reset or complete the deadband on the newly started pwm period. Is that correct?
  • 0 in reply to Nima Eskandari
    TI__Genius 9810 points
    Yes, that's the request.
    Thanks a lot.
    Br, Jordan
  • 0 in reply to Jordan Zhou
    TI__Guru 52020 points
    do you know which would occur? I would think the sync would override the deadband
  • 0 in reply to Nima Eskandari
    TI__Genius 9810 points
    Vasudha,
    Any feedback?
    Br, Jordan
  • 0 in reply to Nima Eskandari
    Intellectual 960 points
    Depends on how you're generating the deadband. The TRM doesn't show any direct interaction between SYNCI and the deadband submodule. If you're generating from OUTA and OUTB from just one internal AQ output (ePWMxA or ePWMxB in figure 14-33 of the TRM), then there should be no problem, since the deadband is set up entirely within the DB submodule, which is unaffected by SYNCI. No matter what happens to the edges of ePWMxA or ePWMxB, the DB submodule will always produce the same delays relative to those edges.

    On the other hand, if you are using both ePWMxA and ePWMxB to generate OUTA and OUTB, then it's plausible that SYNCI might affect the relative timings of their edges (since SYNCI can control the operation of the AQ submodule). This might affect the deadband of OUTA and OUTB. Maybe.

    Also SYNCI feeds into the tripzone module as well, so that's something to check for.