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LP3981 EN Pin

Paul Walker
Prodigy 50 points
Other Parts Discussed in Thread: LP3981, LP3982

Hi.

I would like to know about the voltage range on the EN pin for the LP3981.  I would like to apply a "high" level greater than VIN to the EN pin to enable the part, but the data sheet is not clear on whether I can do this or not.

At first guess, you might answer "NO", because the LP3981 data sheet states under "Recommended Operating Conditions" that the range for the EN pin is from 0V to VIN.  However, a very similar part from TI (the LP3982) has a xSHDN pin (same function as the LP3981 EN pin), and the LP3982 data sheet shows the same Recommended Operating Condition (0V to VIN).  But in the LP3982 data sheet, there is a statement at the end of the first paragraph of section 7.4.1 that states "The xSHDN pin may exceed VIN but not the maximum of 6.5 V".

Since these parts are so similar, can I expect the LP3981 to work the same as the LP3982 in this regard?  Even though I cannot seem to find a statement in the LP3981 data sheet that says this is OK?

Thank you.

  • 0
    TI__Mastermind 22610 points
    Parts might seem similar, but the circuit design is different.

    The only way to know for sure if there is any limitation on the LP3981 EN pin voltage is to bench test some samples.

    I don't have any LP3981 samples in my inventory, they will need to be ordered. I would estimate that it will be about two weeks before I can answer your question with any certainty.
  • 0
    TI__Mastermind 22610 points

    There is no diode between LP3981 EN pin and IN pin.

    You can safely operate the LP3981 EN pin from 0V to 6V, independent of the voltage on the IN pin.