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SN65HVD257: DTO time in SN65HVD275

Oliver Ou
Intellectual 2845 points
Part Number: SN65HVD257

Hi, 

Customer got below waveform  for SN65HVD275 in their system. Would it be caused by DTO time? please give a comment.

Thanks a lot. 

  • 0
    TI__Genius 15345 points

    Hey Oliver,

    What waveform are you expecting to see? How many transceivers are on the bus? If possible could you send a schematic to c-ayoub@ti.com?

    Best,

    Chris

  • 0 in reply to Chris Ayoub
    TI__Intellectual 2845 points

    Hi Chris,

    I have send the schematic by Email.

    Thanks,

    Olive Ou

  • 0 in reply to Oliver Ou
    TI__Genius 15345 points

    Hey Oliver,

    The schematic confirms my previous assumption that there are at least 2 transceivers in this system. I don't think there is a problem here, it just looks like one transceiver's output (Vod) is lower than the other transceiver's output. In the first CAN frame you can see the acknowledge bit of the transceiver pulling Vod higher. Then in the second CAN frame you can see the second transceiver pulling Vod lower as an acknowledge bit. So it seems like your system is working fine and your transceivers are able to communicate.

    This is not a DTO issue since it would disable the transceiver and you wouldn't see anything on Vod. DTO only comes into effect when the transceiver is holding the line dominant for too long. This does not happen in your waveform.

    Let me know if you have any further questions.

    Best,

    Chris