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TCAN1462-Q1: CAN termination resistors

Theo Keinarth
Intellectual 375 points
Part Number: TCAN1462-Q1


Hi TI Team,

I am currently designing a new system in which we use CAN-FD to communicate between system components. The bus is strictly for internal use and does not need to interface with external or third-party CAN devices.

Since we require some external cabling to connect the different system components, we would like to use standard Ethernet cables. We currently use two 60 Ohm resistors with a 4.7 nF capacitor as the termination and the TCAN1462-Q1 as transceiver. 

Is it possible to terminate the bus with 50 Ohm instead, in order to match the characteristic impedance of Ethernet cables?

Thank you in advance.

Best regards,

Theo

  • +1
    TI__Guru 60747 points

    Hi Theo,

    I would recommend to use the 60 ohms resistors even with the Ethernet cable. 50 ohm termination should imply deviating from the ISO standard for an increased drive current (increased heat, lower differential amplitude) and outside the intended operating point.

    I believe standard twisted pair ethernet should be 100 ohms. Hence, CAN bus of 120 ohms being routed over a 100 ohm cable. The difference should still be acceptable as it seems to be about a 9 % ratio for reflection I.e., SIC is designed to tolerate real-world complexities such as this case, thanks.

    Best Regards,

    Michael.