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SN65HVD234: Passive Component Requirement

Nikhil Anjane1
Prodigy 165 points
Part Number: SN65HVD234

Hi Team,

The layout section in the datasheet mentions some passive component on input and output of the IC connections. I understood the use of resistors on RX TX lines to limit current.
My doubt is when I am not using this CAN IC as termination node is there any requirement to use resistors or other passive component on CANH and CANL lines.

Regards,
Nikhil

  • 0
    TI__Guru 69722 points

    Nikhil,

    In most cases, no there won't be a need to place termination resistors at non-end CAN nodes. However, if the connection from the transceiver to the CAN bus is > 0.3 * CAN bus length (physical length), then it is recommended to add high-valued termination to mitigate any signal reflections. We typically recommended 2000 to 5000 ohms termination resistance on non-end CAN nodes, but it will depend on how many nodes in total are on the bus.

    Regards,

  • 0 in reply to Eric Hackett
    Prodigy 165 points

    Hi Eric,

    Thanks for the response.

    So, if the bus length equation comes out true then I need to use 2k-5k ohms for all non-end nodes. Otherwise I can directly connect to the CAN bus and use 120Ohm on terminal nodes.
    Is my understanding correct?

    Regards,
    Nikhil

  • 0 in reply to Nikhil Anjane1
    TI__Guru 69722 points

    Nikhil,

    Yes, that is correct. If the connection of the middle nodes from transceiver to bus is short enough, the reflections created won't exist or they won't effect the signal to the point of causing communication errors.

    For more information, this blog presents the termination concepts and how termination helps mitigate signal reflections, as well as when nodes don't need termination. The interface discussed is RS485, but the concepts are the same for CAN.

    Please let me know if you have any other questions.

    Regards,

  • 0 in reply to Eric Hackett
    Prodigy 165 points

    Eric,

    Thanks a lot for the support.

    The link is a lot helpful.

    Regards,
    Nikhil