This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TCAN1463-Q1: RID(dom)

Part Number: TCAN1463-Q1

Hi TI Expert,

I notice the TCAN1463-Q1 has a parameter called RID(dom).

For the ISO 11898-2, we have to maintain the impedance within 50~60 ohm with 1.5V CANH-CANL.

But RID(dom) is only 40 ohm so I'm wondering whether it will violate the protocol.

Looking forward to your reply.

Thank you.

  • Hi Chia,

    The ISO 11898-2 specification describes that a CAN transceiver must maintain at least a 1.5V differential when the load on the CAN bus (between CANH and CANL) is between 50 - 65 ohms. The CAN specification does not specify impedance requirements for the transceiver itself. The CAN SIC method of controlling transmitter impedance is specific to the new standard and does not conflict with any of the existing CAN requirements. 

    let me know if you have any more questions.

    Regards,
    Eric Schott 

  • Hi Eric,

    Thank you for the comment.

    The reason I think it will violate the standard is because no matter what impedance exist on the bus line will be even smaller after in parallel with 40ohm which is lower than required 50-65ohm.

    Or actually if the CANH-CANL is larger than 1.5V even under 40ohm CAN bus load, it is still acceptable?

    That’s why I’m confused about this part.

    Thank you.

  • Hi Chia, 

    Correct. The transceiver impedance is not a part of the requirement for ISO 11898-2. Only the differential resistance on the CAN bus is considered for these test conditions. 

    Specifying the impedance of the CAN driver is new with the CAN SIC standard, so it is not yet part of the ISO spec. We will likely see this characteristic referenced in the updated ISO 11898-2 when it is revised to include the new CiA 601-4 CAN SIC specification.

    Regards,
    Eric Schott 

  • Hi Eric,

    I see.

    Appreciate your comment.Relaxed