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TS3A27518E: TS3A27518E multiple connections

takahiro higuchi
Prodigy 200 points
Part Number: TS3A27518E
Other Parts Discussed in Thread: TMUX1574,

Hi team,

I am planning to connect several TS3A27518Es.

In this case, is it possible to operate CCLK at 100 MHz?

If it is difficult to operate, what speed would be possible?

Also, could you tell me what precautions should be taken in this configuration?

 

Best regards,

  • 0
    TI__Mastermind 24430 points

    Hello 

    Today is a TI holiday and we will have a response for you tomorrow.

    Regards

  • +1 in reply to Kameron Hill
    TI__Mastermind 24430 points

    Hello

    So after looking at your diagram, I see that you will be passing a signal from one multiplexer to another multiplexer and then the clock signal will finally reach the FPGA. This setup is called cascading multiplexers and we have a app note that covers this in detail.

    1.Because of the cascading setup you have, the bandwidth for the signal passing through both multiplexers will be half of of the multiplexers original values.

    For example

    instead of the bandwidth being 240 MHZ like in the datasheet for this device, your new signal path bandwidth with 2 muxes will be 120MHZ.

    The 120MHZ bandwidth will be to small to and could cause some attenuation to the 100MHZ(clock)signal.

    2.A clock signal ranging from 40 to 80 MHZ should not cause much attenuation because we recommended passing signals that are 1.5 to 3 times less than the signal path bandwidth. Your new signal path bandwidth is 120MHz.

    Is reducing your clock signal an option for your application?

    Please let me know.

    Regards

  • 0 in reply to Kameron Hill
    Prodigy 200 points

    Hi team,

    Thank you for your answer.

    We will check with the customer to see if the clock signal speed can be reduced to 40-80 MHz.

    If we were to control at 100MHz, we think TMUX1574 would be a good choice, is that correct?

    Best regards,

  • +1 in reply to takahiro higuchi
    TI__Mastermind 24430 points

    Hello,

    Yes the tmux1574 is a good choice for this application because its bandwidth is 2GHZ, which is much higher than the TS3A27518E(240MHZ).

    Even if you cascaded two tmux1574's the bandwidth for your signal path would be around 1GHZ which will be more than sufficient for the 100MHZ clock signal.

    To help your customer more you can show them this faq that talks about selecting multiplexers for spi/Qspi applications.

    Please let me know what your customer decides after they take a look at the tmux1574.

    Regards.

  • 0 in reply to Kameron Hill
    Prodigy 200 points

    Hi team,

    Thank you for your response.

    We have checked with the customer and they replied that there is no problem with the clock signal speed of 40-80MHz.
    Therefore, we have decided to proceed with TS3A27518E.

    Best regards,