• State TI Thinks Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 1 answer
  • Subscribers 82 subscribers
  • Views 1456 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TMS320F28335: ePWM deadband delay

BrandonAzbell
Guru 64460 points
Part Number: TMS320F28335

Using Figure 32 in the ePWM user's guide as a reference diagram, I have a question as to the expected behavior on the output(s) of the ePWMxA and ePWMxB signals.

If the original PWM signal input, ie. EPWMxA.in (as illustrated in Figure 31) actually had a the falling edge of the input waveform occur before the rising edge delayed signal occurred, what would the expected EPWMxA output look like?  The modified falling edge is depicted by the red (color) line below.  It is meant to occur before the rising edge of the RED signal.

Would the ePWMA output have a similar waveform as the input, just delayed by RED and FED accordingly?

Or would the ePWMA output be suppressed?

  • 0
    TI__Mastermind 42195 points

    Brandon,

    I have never tried this, Ill ask around if anyone has.

    It may go high after the RED delay. I think this would invert the signal. For example(Signal starts low, FED caused falling action(no effect), RED causes rising action, Signal stays high until the next period's FED, repeat)

    Regards,
    Cody

  • 0 in reply to Cody Watkins
    TI__Guru 64460 points
    Is there any further insight into this inquiry? I would like to understand the logic better and in particular with various settings of FED and RED.
    Thank you.
  • 0 in reply to BrandonAzbell
    TI__Mastermind 42195 points
    Brandon,
    My initial guess was wrong. In the example above if your RED delay is longer than your pulse width the PWM will recognize it as an invalid condition and remain low the entire time. The pulse will effectively disappear.

    To be explicit this is an invalid condition and we do not allow the DB RED or FED delays to become longer than you high or low time.

    Regards,
    Cody