• State TI Thinks Resolved
  • Locked Locked
  • Replies 6 replies
  • Answers 3 answers
  • Subscribers 63 subscribers
  • Views 572 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.

UCC28251: The UCC28251 does not work.

shaowei cui
Intellectual 590 points
Part Number: UCC28251


Hi Ti Engineers,

When the UCC28251 was powered by 5V, the VREF pin has no output.I have checked the layout of PCB，No problems found. I don't know why.(Main circuit is not welded）

Regards,

shaowei.

  • 0
    TI__Intellectual 1390 points

    Hi Shaowei,

    It is strange. You may want to check from below perspectives.

    1) Check PCB to ensure high impendance to groud at VREF, OUTA/B and SRA/B respectively.   

    2)  Swap chip to another to exlcude the possiblity of IC failure.

    Happy debug!

    BR

     Frank

  • 0 in reply to Frank TANG
    Intellectual 590 points
    I have checked what you mentioned. It is still have no output.Can you send me your Email address so that I could send the PCB to you to help me check if it is the PCB that has something wrong.
  • 0 in reply to shaowei cui
    TI__Intellectual 1390 points

    Hi Shaowei,
    Since we are not as familiar with your design as yourself, reviewing your PCB file is not a straight forward way for us to support you on this issue. 
    Could you please get a TI EVM and test the part under 5V bias to see if you can reproduce the same issue as what you saw on your board? If you can, it help us on the same page quickly. If not, you can use EVM as a reference to debug your board.
    Another suggestion on your board debug is to increase VDD voltage a little to see if the issue can be solved. Noticed that the minimum recommended supply voltage of UCC28251 is 4.7V and 5V bias in your application does not leave enough margins.

    BR
    Frank

  • 0 in reply to Frank TANG
    Intellectual 590 points
    Hi Frank,

    I have increased VDD to 15V,The VREF pin just have a little change less than 0.5V,not 3.3V.

    BR
    Shaowei.
  • 0 in reply to Frank TANG
    Intellectual 590 points
    Hi Ti Frank,

    I found a very serious problem.Packaging and schematic mismatch.The schematic library pin of PW-20 on the official website is actually QFN-20.The schematic Library of the two packages is confused.

    Please confirm if this is the case.Please deal with this situation as soon as possible so that I can modify PCB.

    www.ti.com.cn/.../pinout-quality

    Regars,

    shaowei.
  • 0 in reply to shaowei cui
    TI__Genius 13660 points
    Hi Shaowei,

    Your last question has been solved in another post as below link.
    e2e.ti.com/.../745439
    I am going to close this post.

    Regards,
    Teng