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TS3DS26227: Can ts3ds26227 be used to mux PCIe clock?

Adam Torma
Mastermind 45575 points
Part Number: TS3DS26227
Other Parts Discussed in Thread: TS3DV642

e2e,

  1. Can ts3ds26227 be used to mux PCIe clock?
  2. If yes, can we use it between two PCIe switch PHY to control the direction of clock flow?
  3. In the Table3.FUNCTION TABLE of the data sheet, OFF means high impedance or complete open?

Thank you,

Adam

  • 0
    TI__Genius 9132 points

    Hi Adam,

    Can you share details on what generation of PCIe  you are using with TS3DS26227? 

    The typical impedance of all our switches is very high (in the range of Giga Ohm) -  The functional table "OFF" refers to very high impedance. You cannot pass  any signal as the circuit is open.

  • 0 in reply to Saminah C
    TI__Mastermind 18471 points

    up to Gen3 speeds.

  • 0 in reply to Viktorija Cecil
    TI__Genius 9132 points

    Hi Viktorija,

    Looks like the data rate for Gen3 speeds will be up to 8GT/s. So you would need at least 6-7GHz of BW minimum to support those kind of speed. The TS3DV642 is probably the closest one that can support that speed  from MSS portfolio.

    You can also look at some products from the HSI team. Here is the link for the products that support PCIe.

  • 0 in reply to Saminah C
    TI__Genius 9132 points

    Hi Viktorija,

    You mentioned that the clock is at 100MHz.

    We typically recommend selecting a switch with bandwidth that is 3x the fundamental frequency (100MHz in this case).  The TS3DS26227 bandwidth is 800MHz so this should work for their application as long as the signals passing through the switch are within the recommended operating conditions. .

    Thank you,

    Saminah

  • 0 in reply to Saminah C
    TI__Mastermind 18471 points

    Thanks, Saminah. 

    Follow up questions:

    Does the switch pass HCSL (High Speed Current Steering for PCIe clocking)? If the signal fed into the switch is:

    1. HCSL clock at 100 MHZ with +/300 PPM, what will be the PPM at the output of the switch? If the output will have more than +/- 300 PPM, what should be the input PPM so that output will not exceed +/-300 PPM?
    2. LVDS clock at 100 MHZ with +/300 PPM, what will be the PPM at the output of the switch? If the output will have more than +/- 300 PPM, what should be the input PPM so that output will not exceed +/-300 PPM?
    3. Do you see any problem for the switch to drive capacitor coupling as shown in the picture?

  • 0 in reply to Viktorija Cecil
    TI__Mastermind 18471 points

    Saminah, following up on above question from customer. 

    The main question pending is the effect on jitter of the clock as it pass through TS3DS26227?

  • 0 in reply to Viktorija Cecil
    TI__Genius 9132 points

    Hi Viktorija,

    Most of our switches will have +/50 PPM at the output.

    The TS3DS26227 should not cause any issues in your application but let us know if you run into any problem.

    For the coupling capacitor, if you are only passing higher frequencies, it is ok to use it.  It also depends on the value of the capacitor you are using.

    Thanks

    Saminah