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TLC7226: The four ouputs change from operating voltage to 0V without any control.

user5959651
Prodigy 20 points

Part Number: TLC7226

     The TLC7226C outputs connect to max301 directly. Sometimes the four outputs change from operating voltage to 0V .  I can confirm that  Mcu  do not control it. What happened will the output reset to 0V?  

  • 0
    TI__Mastermind 46290 points
    Hello,

    I think we will need more information in order to support this topic.

    Can you please provide a schematic? Additionally any further details concerning how the DAC is being used or what else is happening in the system during this time would be helpful.
  • 0 in reply to Kevin Duke
    Prodigy 20 points

    Hello,

      

        The purpose is  to produce a variable amplitude pulse. The TLC7226  is not broken because its output returned  to normal when  MCU  control it again.  Such a failure is more likely to happen  when  I  connect the

    GND of the oscilloprobe to the GND of circuit board.

  • 0 in reply to user5959651
    TI__Mastermind 46290 points
    Hello,

    I am still not entirely clear on what is happening in the digital domain between cases where the MCU does and does not "control" the DAC. What is happening during this time period? No digital transactions at all?

    Is it possible to trigger a capture with an oscilloscope on the falling edge of one of the DAC outputs to see what happens to the power supply and reference voltages during these events?

    I think it would also be nice to watch for any unintentional activity on the digital bus in the same time period to determine if something is happening there which is unintentionally latching new data.
  • 0 in reply to Kevin Duke
    TI__Mastermind 46290 points
    Hello,

    Any updates on this topic?
  • 0 in reply to Kevin Duke
    TI__Mastermind 46290 points
    Hello,

    In lieu of any updates, I am going to mark this thread as closed. If you do come back with an update feel free to respond and re-open the thread. If the thread has closed, you may ask a related question.