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TCAN4550-Q1: 13 MHz SPI speed

Fabio Soriano
Expert 4720 points

Part Number: TCAN4550-Q1
Other Parts Discussed in Thread: TCAN4550

Hi Team,

 I received the following request, could you please assist?

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We are planing to use TCAN4550-Q1 FD CAN controller, our uC max SPI speed is 13MHz,  

 

1) TCAN4550-Q1 Can operate at 13 MHz SPI speed ?

2) 13 MHz SPI how effects to TCAN4550-Q1

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  • 0
    TI__Guru 74302 points

    Fabio,

    Thanks for bringing this question to our attention. 

    1) The TCAN4550 can operate at a max SPI speed of 18MHz, so 13MHz will be fine.

    2) It won't affect the actual functionality of the TCAN4550. Of course, timing will be affected vs. using a faster/slower SPI speed, but that's not related to the CAN device.

    Please let me know if you have any questions or concerns.

    Regards,

  • 0 in reply to Eric Hackett
    Prodigy 40 points

    Hello Eric,

    You mention about read over SPI will be slower ?

    What I was understanding from your answer, in our case bus speed maximum 5mb/sec.  SPI speed doesn't affect anything.

    My second question is 

    Could you please give us advice about CAN-BUS inductor selection in current product 500 kb/sec 11uH if we increase bus speed up to 5 mbit/sec can we still use same inductors ?

    Regards

    Arslan

  • 0 in reply to Arslan Keles1
    TI__Guru 74302 points

    Arslan,

    Yes, the SPI speed won't affect the datarate of your CAN bus messages. What I meant beofre is that with slower SPI frequency, your throughput to the CAN bus will be slower because SPI messages can't be transmitted and received as quickly as upping the SPI frequency to something above 13MHz but below 18MHz. Ultimately your overall communication time will depend on how much time your SPI transactions + CAN bus communication occur.

    The same inductor can be used at both speeds. The common-mode choke family I see most frequently are the ACT chokes from TDK, though I've run emissions tests with other manufacturer's chokes such as Murata, Coilcraft, and Sunlord, and seen similar results as the ACT chokes.

    Regards,