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LAUNCHXL-F28379D: General CAN BUS test

Renan Santos Adriano
Mastermind 22250 points
Part Number: LAUNCHXL-F28379D
Other Parts Discussed in Thread: SN65HVD234

Hi Team,

My customer would like to confirm if the LAUNCHXL-F28379D is recommended for the General CAN BUS Test (image below). 

He tried to re-create the above testing unfortunately only got 60k ohm on the board.

Thanks in advance.

Regards,

Renan

  • 0
    TI__Guru 62920 points

    Hi Renan,

    60 kOhm seems like a reasonable value to me.  The board uses SN65HVD234 as a transceiver.  That device specifies an input current (when unpowered) of at most 600 uA when 12 V is applied (see "bus input current" spec).  This translates to a minimum input resistance of 12 V / 600 uA = 20 kOhms.  This is normal and doesn't indicate a faulty transceiver.  Note that the CAN physical layer standard (ISO 11898-2:2016) allows for an input resistance per pin as low as 6 kOhm.  Some transceivers do go to a higher-impedance state when unpowered, but not all do.  So, if the goal is just to check for damage to the transceiver I would recommend lowering the failure threshold to below 6 kOhm.

    Max