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LMX2615-SP: SDI, SCK input slew rate requirement

Steve Widener
Genius 11010 points
Part Number: LMX2615-SP


What is the minimum input slew rate for the SDI and SCK pins over process, radiation and temperature?

  • 0
    TI__Mastermind 28021 points

    Steve,

    Unfortunately, we do not have this data and you are the first to ask for this. 

    On other devices, we have seen that 30 V/us is a good number, but this is no guarantee - more of a casual opinion

    As there is no test cover and there are process, radiation, and temperature considerations, I would stay far away from this number.

    The only time I have ever seen this as an issue is when people put low pass filters on their microwire  inputs to reduce EMI.  If you are asking because this is what you are thinking, then I would limit the caps that you put on these to something like 10 pF.

    Regards,

    Dean

  • 0 in reply to Dean Banerjee
    TI__Genius 11010 points

    Dean -

    Would the guidance provided in this document be adequate for our devices? It specifies 10nsec/V as a max slew rate (for LVC)

    Can we assume we can use the information in figure 3 of the following document for the skew rates of the aforementioned parts (LVC)

    http://www.ti.com/lit/an/scba004d/scba004d.pdf

    Steve

  • 0 in reply to Steve Widener
    TI__Mastermind 28021 points

    Steve,

    What this document says seems reasonable. When I say 30 V/us above, this is because at about 20 V/us, I saw issues at room temperature for just one part.  In other words, this is a limit you want to stay far away from.  As we are basing this on speculation and have no characterization data or test coverage for this, 10 nsec/V = 100 V/us sounds like a much more reasonable number.  So I think that this document looks like a good suggestion.

    Regards,

    Dean