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TPD12S016 pullup resistor

Arthur Huang
Expert 6065 points
Other Parts Discussed in Thread: TPD12S016

Hi Team,

customer used TPD12S016 on their IPC system, they found that the DDC signal is failed if they place a 2.2k pullup resistor on DDC terminal(per Intel reference design suggestion), however if they changed the pullup resistor to 100k, the DDC function is worked properly, they want to know why?

Also, per the product data sheet, the DDC line can work properly with no external pullup resistor, so should we need to suggest customer to remove the 100k pullup resistor even though this pullup resistor value is worked?

Please advise. Thanks.

Regards,

Arthur

  • 0
    TI__Genius 12190 points
    Hi Arthur,

    The TPD12S016 has built-in pull-up resistors, so there is no need for external ones. Added external pull-ups are in parallel to the internal ones, lowering the pull-up resistance which in turn will likely fail the specification. The reason a 100 k-ohm pull-up works is the small change in pull-up resistance it has when in parallel with the integrated pull-up resistors. We should suggest to the customer to not use any external pull-ups.

    Regards,