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Original question:

TS3DS10224: TS3DS10224 usage scenario

TS3DS10224: TS3DS10224 usage scenario

Joselito Go
Expert 5880 points
Part Number: TS3DS10224
Other Parts Discussed in Thread: TS3USB221A, TMUX1574, TMUX136

Hi Experts,

Good day.

the customer is having the same usage scenario as described in this post (https://e2e.ti.com/support/switches-multiplexers-group/switches-multiplexers/f/switches-multiplexers-forum/1118745/ts3ds10224-ts3ds10224-usage-scenario?tisearch=e2e-sitesearch&keymatch=TS3DS10224).

Do you still advise using the TS3DS10224 crosspoint or another solution based on 3 mux (as the TS3USB221A) should be preferred?

The signals are High-Speed USB (480Mbps).

Keep safe.

Regards,

Josel

  • 0
    TI__Mastermind 35168 points

    Hey Joel,

    Just to be clear here, the bottom line is that they're trying to be able to create paths between X&Z, Y&Z, and X&Y correct? 

    I wouldn't recommend the TS3DS10244 necessarily here for this since it seems they may not have the bandwidth to support 480Mbps if they need to use it in this configuration. That being said, I don't think a 3 mux solution is needed either. I think we can actually do this in 2!

    Here's a solution I came up with below. Now you can in theory use any 2:1 (SPDT) device with x channels to make this work but you'd want to pick one with enough overhead in the bandwidth to account for the cascading muxes in the Y<->Z situation. I selected the TMUX136 but the 2 x TMUX1574 would work as well. I inserted a truth table as well to give a better idea of the functionality. 

    Device 1 Sel Device 1 EN Device 2 Sel Deivce 2 EN
    X<->Z X High High Low
    Y<->Z High Low Low Low
    X<->Y Low Low High Low


    The idea here would be to short the two devices for the Y<->Z path way then for the X<->Y or Z pathways when they would really only need to pass through one mux they would simply put the non-functioning mux in HI-Z. 

    Let me know if I understood the ask properly and how this solution looks to the customer. Additionally if you had any insight on the customer and their use case, I'd love to here where this application is being used as well.

    Thanks!
    Rami Mooti

  • 0 in reply to Rami Mooti1
    TI__Expert 5880 points

    Hi Rami,

    Good day.

    Thank you for your answer.
    Yes, we want to create paths between X&Z, Y&Z, and X&Y.

    The customer didn't think of this solution indeed.
    Using only 2 mux will reduce the cost of the solution, but what concerns me about the proposed solution is with the Y<->X or X<->Z paths, we will have a very long stub which will affect negatively the signal, right?

    Regards,

    Josel

  • +1 in reply to Joselito Go
    TI__Mastermind 35168 points

    Hey Josel,

    You are correct that stubs will typically negatively affect the signal but at 480Mbps (which if I recall the pulse frequency is actually 240MHz; 2 bits per cycle) and given that we can pretty easily place these muxes very close to each other I wouldn't necessarily think that "very long" stubs will be necessary in the design and at frequencies this low I wouldn't expect that to be an issue. I'd just recommend to keep them as short as possible and with the solution provided, it should be pretty easy to keep them well below 0.5in apart. The flow through routing of the TMUX136 would make this very easy : 



    The only thing they would need to evaluate is if a via is okay on the x- trace. 

    Thanks,
    Rami

  • 0 in reply to Rami Mooti1
    TI__Expert 5880 points
    Hi Rami,


    For the layout, is the way you have in mind?
    I wonder if the way I routed the signals, especially X+ is OK.
    I used 2 vias to pass the X- signal to both muxes.


    Regards,

    Josel
  • 0 in reply to Joselito Go
    TI__Mastermind 35168 points

    Hey Josel,

    I'm not sure if an image is missing here but I don't quite follow what you're asking. Could you please re-ask your question so I can help better here?

    Something I will note though, the image I sent above wouldn't be the finalized routing. You'd probably want to avoid those harsh right angles. I just left it this way for easier illustration purposes.

    Thanks,
    Rami