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DP83826E: DP83826x question on strap resistor configuration

Lauren Mayfield
Expert 7895 points
Part Number: DP83826E

Hi all,

My customer had a question regarding DP83826x.

"

The following table shows the strap resistors that determine the address of the device in the BASIC mode-

Further back in the data sheet it indicates that all 3 of these pins have internal pulldown resistors.  I am confused by the Default state of pin 13 being at ‘1’ and not at ‘0’ if there is an internal pulldown resistor on it.  I plan to use external pullup resistors to set the address for each of the 4 devices in my circuit to overcome the 10K pulldown resistors as recommended by this section-

 

Can you please explain why pin 13 is a ‘1’ by default, and also, what is the Mode column representing?  Is it referring to the Basic or Enhanced mode or is it referring to the state of the pin with or without the external resistor?

  • 0
    TI__Mastermind 39785 points

    Hello,

    This is a typo in the datasheet and we look to correct this in the next revision. Pin 13's state in Basic mode is a PU, which will match the bootstrapping.

    The mode column is referring to which mode you would like to strap the device in per bootstrapping pin. It is the same mechanic for either mode. If you have a PD pin, the default mode is 0. If you would like to keep it that way, no external connections are needed. If you would like to change the mode, please attach a PU resistor of 2.49kOhms to VDDIO.

    Please note that as part of the next datasheet revision, the PU mode 0 Rlo is being changed from 2.49kOhms to 1.5kOhms.

    Sincerely,

    Gerome

  • 0 in reply to Gerome Cacho
    TI__Expert 7895 points

    Thanks Gerome. Do you know when the datasheet will be revised?

    Also, he will change his external pulldowns to 1.5k. Is it correct to assume the external pullups can remain 2.49K?

  • +1 in reply to Lauren Mayfield
    TI__Mastermind 39785 points

    Hi Lauren,

    Yes, the external pull-ups can remain at 2.49k for any internal pull-down bootstrap pin.

    Sincerely,
    Gerome