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Original question:

[FAQ] CAN 5V and 3.3V CAN transceiver operate on the same bus together?

TCAN1462-Q1: TCAN1462 loop delay

Kyle Zhao
Prodigy 210 points

Part Number: TCAN1462-Q1

Hi experts,

I learned that CAN SIC can reduce the ringing from domination to recessive. Reduce loop delay. But I found that there is not much difference compared with the traditional CAN FD. Which application scenarios should you recommend CAN SIC? Why can the cable length be extended?

Best regards,

Kyle

  • 0
    TI__Guru 72302 points

    Hi Kyle,

    Please help see these threads TCAN1472-Q1: The effect of SIC and TCAN1463-Q1: CAN SIC Reduces Bus Ringing, thanks.

    Best Regards,

    Michael.

  • 0 in reply to Michael Ikwuyum
    TI__Prodigy 210 points

    Hi Michael,

    I would like to learn to you. CAN SIC prevents signal reflections through a 100 ohm resistor when dominant to recessive. RS485 for basic function often adds 120 ohm resistors at both ends of the bus. And also to prevent reflections of the signal. Why the basic 485 is ringing is obvious.

    Regards,

    Kyle

  • 0 in reply to Kyle Zhao
    TI__Guru 72302 points

    Hi Kyle,

    So if ringing is obvious, it most likely implies something on the bus is causing impedance mismatch. 

    For example, CAN bus requires two 120 ohm terminations on the bus similar to figure 9-3 of the data sheet and expects an effective bus impedance of 60 ohms. Hence, cable length, bus loading, number of nodes etc similar to 9.2.2.1 of the data sheet can still shift the impedance, observed as ringing.

    CAN SIC supports a better impedance matching (an active drive for a short duration) helping to ensure the ringing is reduced during that time where it would have been obvious similar to the referenced threads with an app note included for more information, thanks.

    Best Regards,

    Michael.

  • 0 in reply to Michael Ikwuyum
    TI__Prodigy 210 points

    Hi Michael，

    Thank you to your reply. You mean CAN bus requires two 120 ohm terminations can't match the impedance well, due to loading or other changes. So CAN SIC can better complete impedance matching on this basis? So in what scenario will they be used? Is the transmission rate above 5Mbps in CAN FD?

    Best Regards,

    Kyle

  • 0 in reply to Kyle Zhao
    TI__Guru 72302 points

    Hi Kyle,

    Any situation that can cause impedance mismatch where ringing is critical due to long cable length, bus loading, number of nodes etc similar to 9.2.2.1 of the data sheet. Yes, higher data rates can also be more susceptible to ringing, but not limited to, thanks.

    Best Regards,

    Michael.