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SN74AVC4T774: Any SPI length limitation on both side?

daniel
Genius 5095 points
Part Number: SN74AVC4T774
Other Parts Discussed in Thread: SN74CBTLV3257,

Hi Team,

Our SPI data rate is 100Mbps, structure as below. level shift (SN74AVC4T774) & switch IC (SN74CBTLV3257)

And the SPI routing constraint is 0 to 4000 mils. Any SPI length limitation on SN74AVC4T774 both side? Or all we have to do is follow SPI routing constraint?

Thanks

  • 0
    TI__Guru* 96591 points
    For logic signal lines, shorter lines are better -- especially at high data rates.

    There are two main areas of concern:
    (1) Parasitic capacitance
    We recommend keeping the load below 70pF (max) and prefer to keep it closer to 15pF for the best operation.

    (2) Transmission line effects
    Once your signal line gets to be longer than a few cm, reflections can cause nonmonotonic behavior. This is very difficult to fix. The best solution is typically to engineer the system to have short signal lines.