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DS90UH949 INTB/REM_INTB

Ryuuichi machida
Guru 11505 points

Hi expert,

Let me double-check about below.

According to datasheet of DS90UH949, both INTB and REM_INTB should be tied to 1.8V.

However, both output pins are open-drain, so I believe that these pins can be tied to 3.3V as well for 3.3V operating micro-controller.

Is my understanding correct ?

Best Regards,

Machida

  • 0
    Guru 11505 points
    Hi,

    Could you please send me your feedback ?

    Best Regards,
    Machida
  • 0
    TI__Prodigy 340 points
    Hi Machida,
    These pins are operating based on 1.8V thresholds, so connecting them to 3.3V would be over the absolute maximum ratings, so it is not recommended.
  • 0 in reply to Tran Dam
    Guru 11505 points

    Hi Tran-san,

    Thank you for your reply.

    I will inform customer that "Please use 1.8V pull up for INTB and REM_INTB of DS90UH949".

    However, I have a question for your answer.

    According to ibis model of DS90UH949.ibs, output buffer of INTB is modeled as 3.3V buffer.

    Here is quote of ibis model.

    13    INTB    bi2c33sfzp18    NA    NA    NA
    14    SDA    bi2c33sfzp18    NA    NA    NA
    15    SCL    bi2c33sfzp18    NA    NA    NA

    [Model]    bi2c33sfzp18
    Model_type    I/O_open_drain
    Polarity      Non-Inverting
    Enable        Active-Low
    Vinl = 0.99
    Vinh = 2.31
    Vmeas = 1.65
    Vref = 3.3
    Cref = 1pF
    Rref = 27000

    According to Datasheet of DS90UH949, actually, maximum voltage of VDDIO is defined 2.5V. However, there is no description of tolerance for INTB and REM_INTB pins .

    Do you know why datasheet is described 1.8V, even though INTB is defined as 3.3V on ibis model ?

    Best Regards,

    Machida