• State Resolved
  • Locked Locked
  • Replies 8 replies
  • Answers 1 answer
  • Subscribers 62 subscribers
  • Views 259 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

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:

UCC28701: UCC28701

UCC28780: ucc28780

robin gangopadhya18
Mastermind 6050 points
Part Number: UCC28780

 Following our posts on UCC28780 application in DC-DC converter-We are stuck so far on the calculations of Cbulk and RPP( which comes out - all the time)

Any clarification on why this is so will be highly appreciated.

We just do not know if these will imply some other values calculated could be wrong as well!

Pl see attached last rev of SLUC644b use for this case.

Your help is highly appreciatedSLUC644B_DCDC_Cbulk_Rpp.pdfsluc664b5V3AMP_EQ30_OCT29­4PM.xlsx.

robin

  • 0
    TI__Mastermind 26840 points

    Hello Robin,

    I believe that this issue has been addressed in yesterday's E2E posting.  This thread has come in some time after that, but is the same topic so I will close this thread.

    As I mentioned yesterday, I'm not sure when a new calculator tool version will become available, but we are working to resolve the negative value results issue. 

    Regards,
    Ulrich

  • 0 in reply to Ulrich Goerke
    Mastermind 6050 points

    yes: this series of posts can be closed.

    I think after your reply with details, we corrected many parameters.

    Most important for us  are the magnetics parameters- if these are correct, we can proceed with pcb fab. Values of all others can be fine tuned later.

    thnx again.

    robin

  • 0 in reply to Ulrich Goerke
    Mastermind 6050 points

    Ulrich

    Problem!

    I had not noticed a dramatic change when I input dc voltage in the "input" section which,  in our case,  is 380V: Vds of the switch shows up as 768V which is way above GaN devices selected & pcb routed.

    Clearly, one would expect such a value from Vin/(1-d) ...but the datasheet does not show any equation for Vds.

    So now, we have to address this, yet better late than after fabrication of the pcb!

    Do you have any neat approach to this?

    My only way would be to series connect 2 low side  switch: but that complicates driving the upper one of the series connection. And that is a whole lot of schematic change. We do have the area available because GaN devices are small. But we double the I2Ron loss.

    Unfortunately, MOSFET is not an option....but  I may have no other way out.

    See attached files pl.sluc664b12V4AMP_NOV3_8AM.xlsx

    Any ideas on this will be greatly appreciated.

    robin

  • 0 in reply to Ulrich Goerke
    Mastermind 6050 points

    Ulrich

    I think I managed to get consistent results out fo the revised spreadsheet SLUC644b. Trivk is what you put in the "input" as you have stated AND HOW YOU SELECT SYNC RECTIFIER DERATING.

    This one is a bit strange.

    So ignore my last attachment on 12v output with 4 amp load.

    Instead,  pl review the new file here. I have 11 such modules in process & I get pretty good results of almost all parameters. 

    There ARE some mishaps in the SLUC644b file though. I can redline them so that you can hope to get them addressed in the next rev.

    This is a very valueable tool-  the E2E community will benefit fromt the corrections.

    Perhaps these are known at TI.

    Let me know.

    robinsluc664b12V4AMP_NOV3_9PM.xlsx

    '

  • 0 in reply to robin gangopadhya18
    TI__Mastermind 26840 points

    Hello Robin,

    I will not be able to look at this in any depth for about a week. However, if you would kindly "redline" the areas you believe need attention, that would help us to find and solve the issues with this calculator.

    Thank you,

    Ulrich 

  • 0 in reply to Ulrich Goerke
    Mastermind 6050 points

    Ulrich

    Of course, I will.

    As I run the spreadsheet for the next module, I will start redlining. Some are really minor, some will be very helpful.

    robin

  • 0 in reply to robin gangopadhya18
    TI__Mastermind 26840 points

    Hello Robin,

    We are working on this issue but the pace is slower than expected due to conflicting duties, unexpected redirections, and limited resources.  We will continue to improve the calculator and release a new version, but I cannot predict how soon that will be and I don't want to make promises that I can't keep.  

    Given this situation, I need to close out this thread, as we are not allowed to keep it open indefinitely.

    For any new issues, please start a new thread.

    Regards,
    Ulrich