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LM5118: FB function inquiry.

David Kim2
Expert 2955 points
Part Number: LM5118

Hi

My customer is conducting a test to control the FB pin with an external signal.
The connection was as follows.
DC Supply (#1) : Input 53V
DC Supply(#2) : FB 2V

However, if DC 2V is applied to the FB pin, the LM5118 dies.
Is there a problem with the test method?
The SCH is as follows.

Thanks

  • 0
    TI__Mastermind 27690 points

    Hi David,

    The engineer responsible for this part is currently out of office and will return back to office next week.

    Regards,

    Richard

  • 0 in reply to Richard Fu22
    TI__Guru 53641 points

    Hi David,

    thank you for using the E2E forum.

    can you explain in more detail what "the LM5118 dies" means?

    I assume that if you say that 2V are applied at FB that you mean you apply this at ADJ.

    -> please conform.

    -> applying 2V at FB will disable the regulation and shut down the output

    Can also add the power stage part, esp. the high side FB resistor connection?

    What voltage do you measure on ADJ when no voltage is applied here?

    What happens to the output voltage if you apply the exact same voltage you have measured above and then slowly change this to the 2V?

    Best regards,

     Stefan

  • 0 in reply to Stefan Schauer
    TI__Guru 53641 points

    Hi David,

    I have not seen an update on this thread for the last 14 days.

    Have all questions now been clarified and answered. 

    If yes, please click on the resolved button, otherwise let me know with the required details.

    Best regards,

     Stefan