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TCAN1043-Q1: CAN bus STB, STG detection

Mahendra Patel1
Expert 3560 points
Part Number: TCAN1043-Q1
Other Parts Discussed in Thread: TCAN1043

Hello Team,

I have a query form my customer on TCAN1043-Q1

Can you please confirm the expected behavior for TCAN1043 during STG and STB for individual lines – CANH / CANL

  • As per CAN physical architecture CANH short with GND and CANL short with Battery has impact in bus function (fault pin of transceiver will sent signal to Micro controller).
  • CANH short to BAT and CANL short to GND does not have any impact on the CAN Bus and it is not defected.

This condition we have tested and detected at bench level. Can you share standard mentioning expected behavior during such conditions? 

 

During fault

No fault

CANH short to Battery

Communication working with no error on bus

Bus recover and no error

CANH short to Ground

No communication and  error message

Bus recover and no error

CANL short to Battery

No communication and  error message

Bus recover and no error

CANL short to Ground

Communication working with no error on bus

Bus recover and no error

-Mahendra

  • 0
    TI__Guru 74292 points

    Mahendra,

    I would expect the nFAULT to assert in any of these cases, but the fact that it doesn't in the CANH short to battery and CANL short to ground cases doesn't surprise me. Communication continuing to work in the CANH short to battery and CANL short to ground cases is expected though. CANH short to Ground and CANL short to battery will stop communication on the transceiver and should indeed report the fault. 

    The way the nFAULT pin works is through a current comparing circuit on CANH and CANL: it compares the current differential of the current out of CANH and the current into CANL. Since the cases of CANH short to battery and CANL short to ground are similar to their normal function, there are scenarios where this won't be detected by nFAULT, and the voltage differential in either case is similar enough where the CAN bus receiver will still interpret the CAN message correctly.

    What data rate is being used in this particular application?

    Regards,

    Eric Hackett