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TCAN1463-Q1: Fault detection on CAN BUS and TX

Isao Takigasaki
Intellectual 2520 points
Part Number: TCAN1463-Q1
Other Parts Discussed in Thread: TCAN1043A-Q1

Hi, 
My customer has 2 questions for TCAN1463-Q1.

1. If any failure is occurred on CAN BUS, can the device detect the failure?  Where, the assumed failures are
        1-1 Either CANH or CANL is short to GND.  As the result, it seems like dominant state on CAN BUS.
        1-2 CANH and CANL are shorted.   As the result the state of CAN BUS seems like recessive.
        1-3 any other cases.

    I think "1-1" in above is detected by CAN BUS Fault flag.  In case of "1-2", The detecting it is difficult, but the short current is limited.
    For "1-3", the device can detect CAN BUS lines shorted to VCC or Vsup also.
    Is my understanding correct?

2. If TXD is held low for long time in active mode or prior to active mode, the device detect TXD DTO or TXDCLP in each case.
    If TXD is unintentionally held high in any case, should any failure be asserted? 

    I think it's not needed and is not implemented into the device, because the purpose of TXD DTO and TXDCLP is to prevent occupying the CAN BUS.   Is my understanding correct?

Best Regards, Taki

  • 0
    TI__Guru 60222 points

    Takigasaki-san,

    Thanks for bringing this to E2E!

    1. Your understanding is correct. For our CAN devices with bus fault detection and SPI, CANH and CANL shorted together is something that can be detected, but for the TCAN1043A-Q1 and TCAN1463-Q1 this is not the case.

    2. No, there is not reporting if TXD is held high, because as you said, it is not occupying or dominating the CAN bus by being in the dominant state. Your understanding is correct.

    Please let us know if you have any other questions.

    Regards,

    Eric Hackett