• State TI Thinks Resolved
  • Locked Locked
  • Replies 4 replies
  • Answers 2 answers
  • Subscribers 83 subscribers
  • Views 1302 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.

Original question:

CCS/TMS320F28035: Peak Current Mode Control Buck Converter

CCS/TMS320F28035: F28035 ePWM DC module blanking diagram

Young (CY) Chen
Prodigy 180 points
Part Number: TMS320F28035


Tool/software: Code Composer Studio

Dear C2000 experts,

I would like to use the function of blanking. But when I'm reading the note, I don't understand about the following description and illustration figure.

According to the content, the behavior should be

offset -> window (end of period), and repeat the same behavior

 However, in the illustration, the offset size or window size are not the same in each cycle. In the case one, for example, the offset size is 5 clk cycle, the window is 6 clk cycle, but in the next period, the offset becomes 4 and the window becomes 5. Other cases have the similar problem, don't they conflict with the highlighted description? 

Expect to know the reason.

Thanks a lot!

Young

  • 0
    TI__Mastermind 42195 points

    Young,

    this diagram is trying to describe that the blanking window does not have to be synchronized to the PWM's period. Meaning the blanking window is not reset because the CTR=0 or CTR=PRD conditions are met, it will continue across a period boundary.

    The diagram above shows what happens under several conditions(1,2,3 from top to bottom in the diagram).

    1. The offset + window are less than the period.
      1. This functions as expected and blanks a short window in the middle of the first period.
    2. The offset + window are greater than the period.
      1. This shows that it is possible for a blanking window to cross a period barrier.
      2. This also shows the offset being reduced before the next period
    3. The offset + window are greater than the period and the offset from the next window will end before the blanking window of the first period. 
      1. This shows what that blanking windows from two periods can overlap without causing issue.

    Regards,
    Cody 

  • 0 in reply to Cody Watkins
    Prodigy 180 points

    Cody,

    Thank you for the reply.

    Based on your explanation and the diagram,

    do you mean the offset and the window would be OK even if the configured sizes of them are different in each cycle?

    thanks,

    Young  

  • 0 in reply to Young (CY) Chen
    TI__Mastermind 42195 points
    Young,
    It should be OK to adjust the blanking offset and window on a cycle-to-cycle basis.

    Regards,
    Cody
  • 0 in reply to Cody Watkins
    TI__Mastermind 42195 points
    I assume this solved your issue, and I will close this thread. If you issue is not resolved feel free to reply here or start a new thread.

    Regards,
    Cody