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TL431: The maximum rating of REF pin

Hirotaka Matsumoto
Guru 27585 points
Part Number: TL431

Hi all

Would you mind if we ask TL431?
How much is the maximum rating of REF pin? 7V?

Our customer assumes that there is the timing to add voltage to REF pin with no Vka.

Kind regards,

Hirotaka Matsumoto

  • 0
    TI__Mastermind 19580 points
    Hi Hirotaka,

    Check out the following E2E thread, it provides information over the REF pin.
    e2e.ti.com/.../450693

    can you describe what you mean with "add voltage to REF with no Vka"?

    -Marcoo
  • 0 in reply to Marcoo Z
    Guru 27585 points

    Marcoo san

    Thank you so much for your reply!
    And then, we apologize that we are late to reply.
    Please refer to the attachment file. 
    20181128_TL431.pdf

    There is the delay of voltage impression. REF -> Vka
    Therefore, we asked you how much the maximum REF voltage with no Vka.
    By the way, is there some limitation Iref with no Vka?


    Kind regards,

    Hirotaka Matsumoto

  • 0 in reply to Hirotaka Matsumoto
    TI__Mastermind 19580 points
    Hi Hirotaka-san,

    There is no issue with the device if REF is below ABS max of 10mA. you can limit the current by using a resistor. I highly recommend having a resistor in series with the REF pin. 1k-10k Ohms.

    When Vka is floating and there is current on REF pin. There is a bit of leakage current that will go from the REF pin into the Vka and you might see a voltage greater than 0V. This voltage is dependent on system components.

    Since there is a delay from REF -> VKA, I do not see an issue if there is a voltage divider or resistor on the REF pin to limit the current to not violate ABS max.

    -Marcoo