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TCAN1044-Q1: TCAN1044-Q1 short circuit test

Jiandong Liu
Intellectual 1801 points
Part Number: TCAN1044-Q1

Hi Expert,

In customer's short circuit test, TCAN1044-Q1 enters bus off mode. However, when short circuit is removed, TCAN1044-Q1 cannot automatically recover normal communication as expected. It must be powered off and powered on again to recover. Is there any method that can makes TCAN1044-Q1 automatically recover, instead of powering off and then powering on? Thanks.

Regards,

Jared.

  • 0
    Guru 316860 points

    Which pins are shorted in this test? The two bus pins?

  • 0 in reply to Clemens Ladisch
    TI__Intellectual 1801 points

    Hi Expert,

    CANH short to GND and CANL short to VCC. After short is removed, TCAN1044-Q1 can't automatically recover normal communication.

    Regards,

    Jared.

  • +1 in reply to Jiandong Liu
    TI__Guru 53555 points

    Hi Jared,

    The device responsible for entering bus-off mode is the CAN controller. When the controller notices enough errors occurring on the bus (like may be caused by a short), it will enter bus-off mode and stop trying to transmit on the CAN bus. In order to return to an active state, the controller will need to receive a restart request or be configured on the back-end. None of this behavior directly impacts the CAN transceiver (TCAN1044) directly. 

    If this is an issue with the transceiver, the behavior would show an unresponsive transceiver (CANH and CANL passive or off) while the CAN controller is attempting to drive data (TXD line active). Can you capture scope shots of the nets listed here? If the TXD line is idle during this time, I would recommend looking into the behavior of the CAN controller in order to exit the bus-off state. If the issue appears to be with the transceiver, please share the scope shots here and confirm that the power supply for the transceiver is stable and the STB input is low.

    Either way, please let us know what you find out and if you have any other questions in the meantime. 

    Regards,
    Eric Schott