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TCAN1042G-Q1: The part does NOT work

Kevin Xiong
Expert 2340 points
Part Number: TCAN1042G-Q1

Hi,

Our customer is using TCAN1042. The symptom of the failing unit is: the TXD pin is always high and the RXD pin is always low. The nomal chip has waveform on TXD and RXD pin.

I confirmed that this issue is relatve with the chip itself by replacement.

So could you please give us some suggestions about this issue?

Thanks.

Kevin Xiong

  • 0
    TI__Guru 74262 points

    Kevin,

    Thanks for bringing this to our attention. Can you explain a little bit more?

    • What kind of application is this and what is the circuit around the TCAN1042? Do you have a schematic you can share?
    • Is this happening on more than one unit?
    • To clarify, the unit failed, so you replaced with another TCAN1042 in the same circuit and it worked fine. Did anything else change with the replaced unit?

    More information will help specify what could be causing this problem.

    Regards,

  • 0 in reply to Eric Hackett
    Expert 2340 points
    Hi Eric,
    Thank you for your reply. Here is my answers:
    1. The application is automotive air-conditioning controller. The customer does not want to share the schematic. But the schematic should be simple according to the datasheet.
    2. It just occurs one unit.
    3. When I replace the new chip, it works fine. The waveform appears on TXD and RXD pin. And the test fixture reports the board is OK.
    From the experiment, the failing unit should be damaged. Do you have more suggestions?
    Thanks.
    Kevin Xiong
  • 0 in reply to Kevin Xiong
    TI__Guru 74262 points
    Kevin,

    Thanks for your answers, without a schematic or layout it will be difficult to pinpoint the issue, is there any way testing can be done on the device? I know it was already removed and replaced from the board, but is there another board you can take measurements on? I'd be curious to know the state of the RXD, CANL, CANH, VCC, and STB pins when the device is powered up.

    Regards,
  • 0 in reply to Eric Hackett
    TI__Guru 62920 points
    Hi Kevin,

    Were you able to take any measurements on the devices that were removed like Eric suggested? If the RXD output is stuck low, you may want to check into the pin's impedance to ground to see if there might have been some damage that resulted in a short-circuit. If the RXD output is always low (dominant), it may cause the CAN controller to enter an error state and drive TXD high (recessive).

    Max