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ISO7763: Signal Delays Through ISO7763 and 1.8V Operation?

Jeffrey Cohen
Prodigy 110 points
Part Number: ISO7763

Dear TI Support, 

I am reviewing a design: The design has a signal flow that has a 48MHz data line going through a ISO7763 and then to a SN74AXC8T245RJWR . The isolator is powered at 3.3V on both sides, and the level translation goes from 3.3V to 1.8V  The signal is UART data at 48Mbps (20.833ns). I was curious as to what speed a ISO7763FDBQR can go from INE to OUTE?  Is the propagation delay symmetric? The PWD Pulse Width Distortion can be as much as 5ns at 3.3V.  Is there a  version of this isolator that can be powered on one side at 3.3V and   1.8V on the other side and that will work for a 48Mbps signal? It would eliminate the level shiftier.

Thank you very much for your help and support,

Jeffrey Cohen

  • 0
    TI__Genius 17100 points

    Hi Jeffrey,

    The ISO7763 propagation delay (time for a signal to reach from input to output) is typically 12ns and ranges from 6 - 16ns. The propagation delay is expected to be the same in forward and reverse channels as long as Vcc1 and Vcc2 are both the same voltage.

    Unfortunately we do not have versions of the ISO7763 or other digital isolators that can be powered by 1.8V, but a level shifter is an optimal solution since UART includes TX and RX signals that need to change from 3.3V to 1.8V and vice versa.


    Is this information helpful? Please let us know if there is more we can provide!


    Thank you for posting to E2E,
    Manuel Chavez


    PSA: Post edited to clarify answer