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MCBTMS570 Development Kit LIN Transceiver Circuit is WRONG.

YuTsun Hsieh
Prodigy 20 points
Other Parts Discussed in Thread: TPIC1021

MCBTMS570 Development Kit use TI's own TPIC1021 LIN transceiver.

The reference application circuit in TPIC1021's datasheet is as below. (This is a cut from page 11 of TPIC1021's datasheet)

 

MCBTMS570 Development Kit’s LIN transceiver circuit is as below. (This is a cut from MCBTMS570 Development Kit’s IO board schematic.)

 

The 1KOhm pull-up resistor should connect to LIN bus not Vsup. Vsup should connect to Vbat. With the wrongly placed pull-up resistor, MCBTMS570 Development Kit’s can not run in LIN master mode correctly. The pull-up will need to be done externally.

  • 0
    TI__Mastermind 22375 points

    ,

    Thanks for using our forum.

    Your comment seems to be correct, and I will contact our engineer in charge for this board for additional comments.

    I will let you know is answer/solution as soon as possible.

    Regards,

    Jean-Marc

  • 0 in reply to Jean-Marc Mifsud
    TI__Mastermind 22375 points

    ,

    We confirm your finding on the pull up for the LIN transceiver

    At this point, we have no plan to build more of this board.
    You will have to fix this problem on your board by replacing R163 by a 0 ohm resistor and to add a 1k resistor between the LIN signal (pin 6 of IC35) and pin 2 of the LIN_MASTER jumper.

    Best Regards,

    Jean-Marc

  • 0 in reply to Jean-Marc Mifsud
    Prodigy 20 points

    Jean-Marc:

    I have done a different modification right after I posted the problem.

    I lifted pin7 if IC35, removed C113 and connected pin6 of IC35 to the pad which is originally for pin7 of IC35.

    It gave LIN signal the needed 1kOhm pull-up and the ability to chose from being LIN master or slave node.

    The lifted pin7 of IC35 was then connected to 12V, pin1 of the LIN_MASTER jumper.

    After the modification, LIN signal works correctly.

    Regards,

    YuTsun