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SN74CB3T3306: My waveform is reversed when it passes through the switch

Part Number: SN74CB3T3306
Other Parts Discussed in Thread: SN74CB3Q3306A



I'm using SN74CB3T3306DCTR , but found the B1 signal is reversed, the waveform as below.

I wonder does it happened in other project or do you have another recommend IC?





Channel 1 : A1 ;

Channel 2 : A0 ;

Channel 3 : B1 ;

Channel 4 : B0


Thank you,


  • Hello Adam,

    We are disappointed to see these scope traces as there should be nothing internal to in our device that should cause this to happen.

    My team has some suspicions as what the issue could be, but we need you to help us by providing a few more scope traces.

    We believe that there could be either an internal short or perhaps a short happening on your board. 

    Since we cannot see where the other signals are coming from, we will suspect it is related to our part for now.

    Could you please provide us with a scope capture of only an input going into channel 1, and nothing going into channel 2.
    Could you also provide us with a scope trace with only a signal going into channel 2 and nothing in channel 1.

    Thank you,

  • Louie,

    I tried to use the SN74CBT3306 and didn't find the issue.  I still feel strange for this issue.

    Thank you,


  • Hello Adam,

    The performance you were seeing with the SN74CB3T3306 is unexpected, however, we cannot continue further investigation without the scope traces.

    I am glad you were able to resolve the issue with the SN74CBT3306.

    Thank you,
  • Dear Louie,

    Sorry for late, the issue was solved after they changed to use SN74CB3Q3306A.