• State Resolved
  • Locked Locked
  • Replies 1 reply
  • Subscribers 33 subscribers
  • Views 126 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TCAN1044A-Q1: Condition which the device enters dominant state

Masaru Oinaga
Expert 4355 points
Part Number: TCAN1044A-Q1

Tool/software:

Hello, Team,

We would like to double check whether our understanding is correct.

Our customer asked us whether pulling TXD from Hi to Lo would make the device output dominant state when a device is in a normal operation mode after power-on.
My understanding is that just turning TXD from Hi to Lo does not make it dominant and it needs the bus signals CANH/CANL to have a differential output (VDIFF>0) as well; correct? (Datasheet 8.3.2)

# Background

Our customer sets the default TXD = Lo when initializing MCU and thought that the device could be in a dominant status unexpectedly every time they restart the system. What they observed was different, where no issue was found and CAN communication was done successfully. Therefore, they wanted to check the details.

Best,
Masaru 

  • +1
    TI__Mastermind 27480 points

    Hi Masaru,

    TXD is integrated pull-up, so if there is no input from MCU it will just output recessive state on the bus.

    Can you double check when your customer set TXD = Low at initializing, they really mean pulling TXD to low (< 0.3 * VCC), or there's just no input to TXD?

    The transceiver also need to be in the normal mode to drive a dominant state. During the initializing, did their MCU pull STB to Low?

    Regards,

    Sean