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WEBENCH® Tools/LM5160-Q1: Switcher's source and ground pin is getting shorted.

ALOK GIRI
Prodigy 60 points
Part Number: LM5160-Q1

Tool/software: WEBENCH® Design Tools

Dear TI Team,

 

I have designed a Flybuck converter for 44Vin to 54Vin at 12Vout-iso, 1.2A using Webench. kindly find the design report in attachment, in order to get 12V output i have changed the values of rfbb and rfbt resistors , while operating at 44V initially the circuit works and shows the desired output voltage but after few cycles the switcher ic's pin (ie Vin and gnd) is getting shorted internally. kindly address me what possibly could be the reason. Final_48V-to-12V_Converter-7_Nos.pdf

  • 0
    TI__Mastermind 23845 points

    Hi,

    Do you use the same transformer part number that is recommended by webench?

    Also, do you test this on our EVM?

    Thanks

    -Arief

  • 0 in reply to Arief Hernadi
    Prodigy 60 points

    Hello Arief,

    yes, I have used the same transformer part number that is recommended by webench, the green waveform shown in the attached image is the voltage across the primary side of the transformer which have oscillations while switching,could it be the reason?.output is 15V instead of 12V because i still have to size the values feedback resistors.

    I have not tested in your EVM, find my schematic circuit in the attachment

    I have designed pcb layout accordingly.

    Regards,


    - Alok 

  • 0 in reply to ALOK GIRI
    TI__Mastermind 23845 points

    Hi Alok,

    The switching in the transformer should happen because the transformer will transfer the energy to the secondary of the circuit. 

    Is the part damaged after loading at the primary or secondary?

    Can you try to load the primary output voltage and ensure you maintain regulation and stability?

    Also, it's a good idea to double check against an EVM and we can send you one if you prefer

    Thanks

    -Arief

  • 0 in reply to Arief Hernadi
    Prodigy 60 points

    Dear Arief,

    I have connected my load at secondary in order to get isolated output, kindly explain me how connecting load in primary will ensure stability? I  would like to cross check with your EVM, can I a get a sample.

  • 0 in reply to ALOK GIRI
    TI__Mastermind 23845 points

    Hi Alok,

    On a flybuck design, the regulation happens at primary. Therefore i want to ensure stability first by trying to see if the primary side of regulation is ok. 

    If you have an address, i can send an EVM to you

    Thanks

    -Arief

  • 0 in reply to Arief Hernadi
    Prodigy 60 points

    Hello Arief,

    Do i need to pay for the EVM sample?

  • 0 in reply to ALOK GIRI
    TI__Mastermind 23845 points

    Hi Alok,

    No, i can send you one if you are located within the USA.

    Just let me know your shipping address

    Thanks

    -Arief

  • 0 in reply to Arief Hernadi
    Prodigy 60 points

    Dear Arief,

    This is to bring you kind notice that i understood the flaw in my circuit and i successfully tested the design at rated condition.Thank you! for your support.

  • 0 in reply to ALOK GIRI
    TI__Mastermind 23845 points

    Hi Alok,

    Sounds great. I am glad that you are able to resolve the issue

    Thanks

    -Arief