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TCAN1043A-Q1: Silent Mode

Josef Warta
Expert 4130 points
Part Number: TCAN1043A-Q1
Other Parts Discussed in Thread: TCAN1043,

Hello Team, customer has following issue with our TCAN1043A-Q1 (after changing it from TCAN1043 which was before used and works)

It seems that the CAN bus stays in resistive mode and didn't send no longer data.

Enclosed screen-shots of the signals TxD, CAN_L, STB and EN pin. nFAULT-pin is always high

Seems that transceiver stays in silent-mode after start-up even EN and STB are set high.

Any advice where to look?

Many Thanks

Josef

  • 0
    TI__Guru 50835 points

    Hi Josef,

    It looks like this is probably occurring due to the TXD clamp (TXDCLP) behavior for TCAN1043A that is different TCAN1043. This feature requires that the TXD pin is high when normal mode is entered to ensure there is not any glitch inserted on the CAN bus during startup. The TCAN1043 simply blocked the transmission until TXD was high again. TCAN1043A by comparison requires a mode change in order to re-enable the driver after this fault has occurred. 

    My recommendation is to update the order of operations in the software so that the TXD signal is high before the transceiver is placed into normal mode. This will prevent the TXDCLP behavior from being used in either the TCAN1043 or TCAN1043A and prevent inadvertent transmissions during startup if other transceivers without this feature are used. 

    I'm also noticing that there is a significant delay between the EN and nSTB signals be driven high. Because this delay is longer than the minimum time for tGOTOSLEEP, it is possible that the transceiver may be momentarily driven into sleep mode. This should be avoided as it will impact the INH signal which could have further impacts on the system level. Please drive the EN and nSTB signals high with 20us of each other or change the order in which they are driven high so that go-to-sleep mode is not entered during this transition. 

    Let me know if you have any more questions. 

    Regards, 
    Eric Schott

  • 0
    Prodigy 20 points

    Thank you for the information. TXD-Pin state was our problem. TCAN1043A  is working as expected, when we change the TXD-Pin state high.