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TCAN1042H-Q1: CAN/LIN Loss of GND

Muwei Zheng
Intellectual 2000 points

Part Number: TCAN1042H-Q1
Other Parts Discussed in Thread: ISO1042

Hi team,

My customer is discussing CAN and LIN compatibility during ground floating in 48V/12V mixed systems.

The new ISO25769 specifically includes waveform examples regarding ground floating for CAN in APPENDIX-D.

Could you share your feedback if you already have any countermeasure solutions to loss of GND?

Thank you,

Muwei Zheng

  • 0
    TI__Guru* 77652 points

    Hi Muwei,

    The data sheet specifies ± 30 V for large ground shifts between nodes. Hence, this allows operation and may be included in such discussions.

    You may see figures 2-3 and 2-4 from this app note as examples for the GND shift discussion, thanks.

    Best Regards,

    Michael.

  • 0 in reply to Michael Ikwuyum
    TI__Intellectual 2000 points

    Hi Michael,

    Thank you for your explanation. Actually customer want to know if we have any specific countermeasure to pass ISO25769 test. Below is a part of the ISO standard and voltage shift could be over +/-30V. Do we have any assessment on passing ISO25769 for any of TCAN device? or any protection circuit is needed to pass ISO standard?

    Regards,

    Muwei Zheng

  • 0 in reply to Muwei Zheng
    TI__Guru* 77652 points

    Hi Muwei,

    Unfortunately, the data sheet s as specified and the passing ISO25769 should be system dependent, rather than just  transceiver dependent.

    Hence, would recommend improving the ground reference by adding a low impedance return path / ground straps / shield grounding / dedicated return conductor to help reduce common mode shifts.

    • Also, CMC + split termination should help control the common mode and keeping CANH / CANl within range during floating. 
    • TVS diodes > the 30 V events.
    • Current limiting series resistors (10 to 33 ohms, adjusted as needed) on CANH / CANL.
    • If any additional concerns after the above recommendations, may further consider isolation transceivers such as ISO1042 for example, thanks.

    Best Regards,

    Michael.