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MUX36S16: Unpower mux performance

Joseph Borrelli
Prodigy 40 points

Part Number: MUX36S16
Other Parts Discussed in Thread: TMUX7308F

To TI product support,

  We have a design considering the MUX36S16 to multiplex external signals.  The external signals may be powered when the MUX36S16 is depowered.  I want to avoid loading the external signals or SCRing the MUX36S16.  Is the MUX36S16 dielectrically isolated to support this situation?  If not, does TI have a product for this application?

Regards,

Joe Borrelli

  • 0
    TI__Genius 13395 points

    Hi Joe,

    The inputs of this mux cannot be less than VSS or greater than VDD. Thus, if the mux is powered off, the input signals must also be off. Depending on the voltages of your signals, we may have a few options for you in our beyond the supply mux portfolio. One option in that portfolio is the TMUX4819, a 15V 2:1 mux. You could connect multiple of these muxes together to get a different configuration such as 8:1 or 16:1.

    Best,
    Katy

  • 0
    Prodigy 40 points

    Katy,

      Thank you for your response.  I was not aware of the TMUX switches.  Using multiple parts would be a burden in this design.  Looking for something equivalent to the HI506 type muxes.

    Regards,

    Joe B

  • 0 in reply to Joseph Borrelli
    TI__Genius 13395 points

    Hi Joe,

    Understand that multiple muxes would not be ideal. However in checking out the HI506 muxes, it seems they also have same restrictions - the input signals cannot go beyond VSS-2V or VDD+2V, meaning that when the device is powered off, the input range can only be between -2V and 2V. These are the same exact absolute maximum ratings as the MUX36S16 device. 

    If you need to be able to have voltage on an input when the mux is powered off, I would suggest searching for other beyond-the-supply muxes or powered-off protected muxes, because traditional muxes are not going to work here!

    Best,
    Katy

  • 0 in reply to Katy West
    Prodigy 40 points

    Katy,

      The complete legacy part number is MPC506A.  These parts can take 20V above or below the rails, which is adequate for our application, as shown below.  These part a large and expensive.  Looking for an updated solution, if one exists.

    Regards,

    Joe B

  • 0 in reply to Joseph Borrelli
    TI__Genius 13395 points

    Hi Joe,

    Thanks for clarifying the part number. The closest option to what you are looking for is going to be one of our fault-protected muxes that has over-voltage protection on the input (S) pins. We have an 8:1 option here with OVP up to +/-60V - TMUX7308F. 

    I will make a note to add a 16:1 OVP mux to our backlog.

    Best,
    Katy

  • 0 in reply to Katy West
    Prodigy 40 points

    Katy,

      This TMUX7308F device looks promising.  I will review the datasheet in more detail.  I like that fact that the digital pins require lower input voltages than the legacy parts.  I appreciate your support!

    Regards,

    Joe B