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LP5907: EN input signal slew rate

Koshi Ninomiya
Expert 4350 points
Part Number: LP5907

Hi Team,

My customer is considering to use LP5907SNX-3.3. And there is a question about the slew rate of EN input signal.

Q: Are there any limitation of slew rate of EN input signal rising?

Thank you.

Best Regards,

Koshi Ninomiya

  • 0
    TI__Mastermind 44600 points

    Hi Ninomoya-san,

    The only issue with a very slow slew rate of the EN input signal is that enable/disable threshold:

    Below 0.4V we guarantee that the device will be off. Above 1.2V, we guarantee that the device will be on. Between 0.4 and 1.2V, the device is in an undefined state.

    What is the slew rate your customer is concerned with?

  • 0 in reply to JCHK
    TI__Expert 4350 points

    Hi John-san,

    The customer is going to use two LP5907s.
    EN input signal to the 1st LP5907 rises from 0V to 4V with 0.11ms. So, Slew Rate is 36.4V/ms.
    But if it is possible, they want to slow the EN signal as 1.2ms from 0V to 4V. So, Slew Rate is 3.3V/ms.

    EN signal to the 2nd LP5907 is half voltage of the 3.3V output from the 1st LP5907 by divided 100kohm & 100kohm resistors.
    The 3.3V output from the 1st LP5907 rises from 0V to 3.3V with around 120us.
    The EN signal to the 2nd LP5907 rise from 0V to 1.65V with around 120us, So, Slew Rate is 13.8V/ms.

    The above slew rate of EN input signal are OK?
    Thank you.

    Best Regards,

    Koshi Ninomiya

  • 0 in reply to Koshi Ninomiya
    TI__Mastermind 44600 points

    Hi Ninomiya-san,

    We have not heard of any issue with the slew rate of the enable pin other than the potential issue where between the logic thresholds where the device operation is undefined.  Once the enable is above 1.2V the device will work as specified.

    I hope this helps to answer your question.