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Original question:

TLV702: /EN pin current

TLV702: Is there any internal pull-up or pull-down on the EN pin?

Southern Engineering
Intellectual 715 points
Part Number: TLV702

Hi,

Did tests with TLV70233DSE in a design where there for historical reasons is 10k in series with the EN pin (between MCU control pin and LDO EN pin) and noted that when driving the MCU pin low the EN pin did not go to 0V, but rather to 200mV. My input voltage is ~4.5V, so I was considering that perhaps there is an internal pull-up of ~200kOhm that explains this behavior, forming a voltage divider with my 10k. However, I do not find any such indication in the datasheet.

Is there any internal pull-up (or pull-down) on the EN pin?

Thanks!

  • 0
    TI__Guru 50090 points

    Hi,

    There is no intentional pull-up on the enable pin. What you are likely seeing is leakage which may vary over parts and temperature. Can you verify this to see if it changes over temperature?

    Regards,

  • 0 in reply to JCHK
    Intellectual 715 points

    Hi,

    Thanks for the feedback. I will see if I can do some tests.

    I have two follow-up questions based on this assumption, if you do not mind. If this is leakage, it appears to me it would correspond to ~20uA (4.5V/200k) at room temperature if I pull the EN pin low.

    1) Are there any suggestions on how to avoid this level of leakage? In my application every uA present in "off mode" might be of interest.

    2) I was planning to have the LDO disabled per default with an external 100k pull-down. Is it safe to say then that it would have to be a smaller value (such as 10k) to ensure that the pin really is low (<0.4V)?

    Thanks!

  • 0 in reply to Southern Engineering
    TI__Guru 50090 points

    Hi,

    If every uA of current matters, you should have a look at our latest TPS7A02. This LDO has only 25nA of IQ and the leakage on its EN pin is only 10nA. 

    To answer your questions:

    1. Not really, A different LDO with less leakage is probably best

    2. Yes, that should help to guarantee it is off, but the smaller the resistor the better. 

    I hope this answers your question.

  • 0 in reply to JCHK
    Intellectual 715 points

    Hi,

    Understood.

    I got my hands on additional units and was not able to reproduce the behavior. With limited time I will leave it at that for now and keep an eye open for this behavior on coming units.

    Thanks!