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CD74HC4052: shorting ON channels

Kurumi Hasegawa
Expert 7111 points
Part Number: CD74HC4052

Hi team,

 

Would there any possibility of shorting ON channels when changing input status?

For example, when switching from (S1,S0)=(L,L) to (L,H), is there any chance that A0 and A1 shorted?

Or, is there any integrated protection features?

 

Best regards,

Kurumi

  • +1
    Guru 295670 points

    "Break-before-make" means that this is avoided.

  • +1
    TI__Genius 10974 points

    Hi Kurumi,

    As Clemens mentioned, these devices offer what is a "break-before-make" delay. This means that when you try to change inputs, the currently selected channel will disconnect for the "break-before-make" delay time and then the desired channel will be switched on once that delay expires. Thus, this protection feature will allow the device to avoid the potential shorting of two channels together.

    Thanks!

    Bryan

  • 0 in reply to Bryan Marshall
    TI__Expert 7111 points

    Hi Clemens and Bryan,

    Thank you so much for the quick reply, I understand it is Break-before-make so there is no chance for the shorting. I also found the term of the datasheet.

    Is there any delay parameters or timing chart showing how Break-before-make protection is implemented?

    Which delay parameter indicate "break-before-make" delay time?

     

    Best regards,

    Kurumi

  • +1 in reply to Kurumi Hasegawa
    Guru 295670 points

    There is no guaranteed specification for this.

    But you can get an estimate from the difference of the maximum switch turn on delay and maximum switch turn off delay.

  • 0 in reply to Kurumi Hasegawa
    TI__Genius 10974 points

    Hi Kurumi,

    Let me look into this and get back to you.

    Thanks!

    Bryan

  • +1 in reply to Bryan Marshall
    TI__Genius 10974 points

    Hi Kurumi,

    Please see below for an example of "break before make" (tbbm):

    As you can see in the above illustration, once the logic changes, the output will be left essentially floating before connecting to the new channel.

    Unfortunately, we do not specify this exact timing in this datasheet for this device, however, to be safe you can utilize turn off/turn on delays as the maximum time needed to ensure enough time between channel switching.

    Thanks!
    Bryan

  • 0 in reply to Bryan Marshall
    TI__Expert 7111 points

    Hi Clemens and Bryan,

    Understood, thank you so much for the help!

    Best regards,

    Kurumi