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MSP432P401R: Need Values for Noise Margin Calculation

Anoop Kumar K V
Prodigy 180 points

Part Number: MSP432P401R

Please help me to get the Voh(min),Vih(min),Vol(max) and Vil(max) values for I2C lines(SDA and SCL).

  • 0
    TI__Guru 70606 points

    Hello Anoop,

    From the datasheet, for VIH and VIL see:

    For the VOH and VOL, since I2C bus is an "open-collector" drive scheme, the IO port pin does not actively drive the pin high, it is pulled up to VCC using resistors.

    VOL should be considered though.  As you can see from the graph, VOL will vary with the current flowing through the pin.  That is calculated by VCC/R, where R is the pullup resistance.   Example 3.3/10k = 330uA.

    Now looking at the graph, 330uA would produce a very small voltage drop, well below the VIL input threshold of the other devices on the bus, such as another MSP432 (From chart above, min is 0.55v).

    Does this answer your questions?

  • 0 in reply to Dennis Lehman
    TI__Guru 70606 points

    Hello Anoop,

    I haven’t heard from you for a couple of days now, so I’m assuming you were able to resolve your issue.
    If this isn’t the case, please click the "This did NOT resolve my issue" button and reply to this thread with more information.
    If this thread locks, please click the "Ask a related question" button and in the new thread describe the current status of your issue and any additional details you may have to assist us in helping to solve your issues.

  • 0 in reply to Dennis Lehman
    Prodigy 180 points

    Understood about Voh and Vol values. We are powering MSP432 with 3.3V supply. What will be the values of Vih(min) and Vil(max)? Can you explain little bit in detail?

  • 0 in reply to Anoop Kumar K V
    TI__Guru 70606 points

    Hi Anoop,

    The values will be ratio metric.

    Going from 3.0v to 3.3v is a 10% increase, so you would increase the VIH and VIL by 10%

    Example: from the chart above, let's take VIT+ max which 2.35v when VCC = 3.0v.

    Using this formula you can calculate what VIT+ would be at 3.3v

    Dennis

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