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SN65HVD09: Channel to Channel Skew

Nirmal Bommu
Prodigy 60 points
Part Number: SN65HVD09

In Datasheet they mentioned individual Channel Pulse Skew rate as 4ns. But In my case I am connecting all the inputs to get 8 channel outputs (for GPS PPS Signal).

My doubt is that,

Whether Every channel has same skew rate or is it differ from one another?

Whether every channel give output at the exact time ?

  • 0
    TI__Guru 52022 points

    Hi Nirmal,

    So we don't have direct data on this for the channel to channel skew measurement, however, the data we do provide can help point towards an estimate.

    Essentially channel to channel skew is the difference in propagation delays between different outputs. The propagation delay for this part ranges between 2.5ns and 13.5ns - this is highly temperature dependent - the colder the part the closer to minimum the hotter the part the closer to maximum you will get. This is the same for every channel - which also implies you won't have a part with one channel at 2.5ns and one at 13.5ns for the same temperature and operating conditions. The max difference between low to high and high to low transitions(at max temperature as well) is 4ns - this is the individual channel skew as mentioned.

    With that information known as well as the fact that the drivers have the same architecture and will be in same conditions you shouldn't see a max skew much larger than the individual skew of each channel ~4 - 5ns is probably in the range of what you will be looking at. I am not super familiar with GPS specific PPS signals, and I know the skew this part  has can be in range for some PPS signals but not all as some PPS need very tight skew budgets - so what is the skew you are looking at for this specific application as that may be a better judge if this part will be a decent fit.

    So for your overall question - no the signals will not necessarily come at the same time because there will be some skew - but it shouldn't be much higher than the max individual pulse skew - depending on the accuracy needed by the PPS signal - this part may work it really depends on how tight your skew budget is - if you could let me know I may be able to give you a better indication of if this part will be okay or not, but in general I would put it at a few ns and it will be better in cooler conditions. 

    Please let me know if you have any other questions!

    Best,

    Parker Dodson