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THVD8000: R pin output pulse

Allen Lu
Intellectual 1870 points
Part Number: THVD8000

Hi team,

 we are seeing the MODE signal of THVD8000 is off for about 2us, there is a probability of outputting a 0.5us low-level pulse from the R pin. Is there any possibility to cause this pulse?

Green is MODE, purple is R

  • 0
    TI__Mastermind 45687 points

    Hi Allen,

    What is the yellow scope shot represent?

    Also if it is possible to share differential bus signal - both the A and B pins would be much appreciated. 

    Also if possible can you share the schematic being used - please email me if you can't post the schematic on the forum and I can answer you there as well. 

    Best,

    Parker Dodson

  • 0 in reply to Parker Dodson
    TI__Intellectual 1870 points

    Hi Parker  

     add more details for checking:

    When testing THVD8000, we found that the R pin of the chip has a probability of outputting an incorrect level, as shown in the blue line in the figure below.
    The green line is R to ground, and the red line is the waveform of chip A to B.

    After enlarging the above picture, you can see that when R outputs low level (the maximum low-level pulse width is measured at 1.7us), the voltage between the AB lines is not disturbed, as shown in the figure below.

    In addition, the abnormal low level of the R pin appears about 2us after the MODE signal changes from high level to low level, as shown in the figure below.
    Red is R to ground, green is MODE to ground.

    What is the cause of the above exception? tks for the checking.

     

  • 0 in reply to Allen Lu
    TI__Mastermind 45687 points

    Hi Allen,

    I haven't seen this issue in the past before from this device - and the behavior does seem pretty odd

    Can you please email me the schematic being used so I can verify the configuration of the device - or you can post it here either way works for me. 

    Also can you post a picture of the top of the unit being tested so I can trace it back into our system. 

    Best,

    Parker Dodson