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TLIN1021A-Q1: Suggestions on disconnecting slave GND and Mater GND.

Fabio Gou
Expert 4455 points
Part Number: TLIN1021A-Q1

Tool/software:

The green one is the Vsup in slave board.(8V)

The blue one is the LIN bus voltage. (Mater side voltage is 14V)

In the special test, the customer will disconnect slave GND and Mater GND.

When testing the voltage between LIN bus and  Slave GND, the voltage is -7V~7V, which will cause communication error.

Could you provide some suggestions how to avoid this? (Avoid the impact of difference between GND_Slave and GND_Master)

  • 0
    TI__Guru 52166 points

    Hi Fabio,

    This is expected as a common reference is required.

    The reliable fix would be to give the slave a reference to the master ground or isolate the LIN node to avoid being driven relative to the slave ground.

    Hence, I would recommend to keep GND common to avoid properly interpreting the bus voltages from the test disconnecting the ground. You may also consider replacing L3 or L4 with a 33 -100 ohms series resistor to verify, thanks.

    Best Regards,

    Michael.

  • 0 in reply to Michael Ikwuyum
    TI__Expert 4455 points

    Hi Michael, 

    Sorry I did not get your suggestions.

    How to keep the GND common? The test requirements are disconnecting Slave_GND and Mater GND. As mater GND is in another board and  the connection is by the wire.

    I guess this should be a common test. As the ECU board GND connect to Master board GND by the wire.

  • 0 in reply to Fabio Gou
    TI__Guru 52166 points

    Hi Fabio,

    Please note that GND is needed for normal communication. Hence, not having ground is abnormal and the test should not be expecting normal communication with abnormal conditions. The suggestion is to fix the harness. You may run a ground shield / return in the same wire as the LIN or tie the chassis GND references together. I.e., ensure the test keeps a low impedance ground return during normal operation when the test forces a GND disconnect as normal operation requires a proper ground, thanks.

    Best Regards,

    Michael.