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LM4121: open/short test

Kaji@PAN
Mastermind 7220 points
Part Number: LM4121

Hi,

I am considering open / short test of LM 4121 - ADJ.

I am now setting the upper resistance of the attached figure to OPEN.
At that time, I think VOUT will rise. Probably up to about VIN - 0.2V.
What happens to IC after that? Does the IC destroy?
I do not know because there is no description of the maximum rating of VOUT in the data sheet.

Best regards,

  • 0
    TI__Mastermind 19470 points
    Hi Kaji@PAN,

    As long as the Vin is within the datasheet specifications, there should be no damage by having Vout rise to Vin - Vdrop. I would say to try to keep Vout within 1.25V - 10V like in figure 31. It should not be possible to raise Vout above Vin.

    I can try this at the bench but it might take a week or so to get results. Is there a specific voltage you are looking at?

    -MZ
  • 0 in reply to Marcoo Z
    Mastermind 7220 points

    Thank you for your reply.
    I am glad if you can try it.

    (Specification)
    Vin=5 V
    Vout=3.0 V
    Ioutmax=1mA(0.5mAtyp)

    (Project information)
    APP:MEDICAL HEALTHCARE(Drug Injector)
    Production Date:2018/10/01
    System/Year:108,000

    Best regards,

  • 0 in reply to Kaji@PAN
    TI__Mastermind 19470 points
    Hi Kaji@PAN,

    It took me longer than expected to test this on the bench but I still wanted to get this out.

    In a short instead of R1, the LM4121 goes to its default VREF 1.216V.
    In an open instead of R1, the LM4121 goes to VCC - Vdrop. Where Vdrop depends on the current from figure 27 on the Datasheet.

    I do not recommend using the LM4121 for a Vout greater than 12V. It will not function as expected above 12V until it power recycles.

    In your application:

    Vout (Short) = 1.216V
    Vout (Open) = 4.98V

    If you have anymore questions, feel free to ask.

    -MZ

    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


    If you feel this is resolved, please selected Answered.
  • 0 in reply to Marcoo Z
    Mastermind 7220 points
    I greatly appreciate your reply.
    I understood about the test results.