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ISO1050: 120ohm termination

na na78
Guru 16770 points
Part Number: ISO1050

Hi

Now the 120Ωtermination is not populated, but the amplitude of CAN signal seems to be fine.

Do you think it is necessary to populate 120ohm termination for this circuit?

BestRegards

  • 0
    TI__Expert 6195 points
    Hi,

    I think this will depend on what is at that connector. It is a requirement in a CAN system to have termination resistors at the furthest nodes. 120 ohms comes from the characteristic impedance of the twister wire pair. The requirement for termination is due to the fact that only the dominant state is driven; the bus is never actively driven to the recessive state. The termination resistor passively returns the two wires to a nominal differential voltage of 0V.

    If this is just one node connected to the bus and is not the first or last node (the two that are farthest apart), then the 120 ohm is not needed here.

    Let me know if you have any questions!

    Best regards,
    Dan
  • 0 in reply to Dan Kisling
    Guru 16770 points
    Hi Dan

    Thank you for your reply.
    I understood.

    BestRegards