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SN65LVDS051: SPI over LVDS over RIBBON CABLE

Ian Benton
Prodigy 110 points
Part Number: SN65LVDS051

Tool/software:

I have read your various application notes about SPI over LVDS. My required data rate is quite modest (8Mbit/sec) and cable length is 2m.

Just how bad would ordinary (non-twisted-pair) ribbon cable be? (I've got lots of it)

I understand that the crucial signal is SCK because nothing else matters on MOSI and MISO at any time other than SCK edges. 

Could it be improved by 0V signals either side of SCK, or by interspersing MOSI and MISO with CS signals that only change once in a while?

Would the 65C1168 be better or worse?

  • 0
    TI__Genius 15321 points

    Hello,

    I have been out of office and I will get back to you this week.

    Thank you, Amy

  • 0
    TI__Guru 72597 points

    Ian,

    An engineer has been assigned to this post and will review and respond by 08/01/2024 end of business CST.

    Regards,

    Eric Hackett 

  • 0
    TI__Genius 15321 points

    Hi Ian,

    I have seen a general recommendation for LVDS that ribbon cable is generally okay for short distances (< 0.5 m), but I do not have a supplemental source to point to support this specifically. We do have this resource that explains the Performance of LVDS with Different Cables (Rev. B) (ti.com). Twisted pair cabling is recommended over coax, as this provides two identical conductors that transmit a signal and it's complement. Any noise or distortion will impact both conductors equally, meaning the differential signal will not change. If it is important to have a clean SCK signal, then the twisted pair cabling would be preferred over ribbon cabling. 

    Regards, Amy