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DS110DF111: REFERENCE CLOCK

Sean Iwasaki
Intellectual 400 points
Part Number: DS110DF111
Other Parts Discussed in Thread: DS110DF410, DS250DF410, DS250DF230

Dear TI Technical Support:

I have a new design which will involve two (2) to four (4) DS110DF111 parts.  Can I use a single 25 MHz 25ppm clock oscillators to connect to 2 - 4 DS110DF111 parts? 

Depending upon the PCB layout, I may need to add a low impedance series series resistors or buffers.

Thank you

  • 0
    TI__Mastermind 43795 points

    Hi,

    It may be possible to produce a layout to support multiple DS110DF111 devices with a single clock oscillator.  I would recommend to do some IBIS sims to understand how your specific oscillator signal integrity would be effected by multiple transmission lines and device loads. 

    Our reference design material uses 1 oscillator per DS110DF111.  Another approach would be to use a DS110DF410 which has a REFCLK Output.  This would allow a couple DS110DF410 devices to be serviced by a single clock oscillator.

    Regards,

    Lee

  • 0 in reply to Lee Sledjeski
    Intellectual 400 points

    Lee:

    Thank you for your quick reply.  I will probably use a separate clock oscillator for each device.  The DS110DF111 provides the loopback function which the DS110DF410 and its variants.  Unfortunately, the DS250DF410 does not include this function as well. 

  • 0 in reply to Sean Iwasaki
    TI__Mastermind 43795 points

    Hi Sean,

    The DS250DF230 could be an option for you at 25G rates.  It includes a 2x2 crosspoint in the datapath.  This could be used as a loopback function.

    Regards,

    Lee

  • 0 in reply to Lee Sledjeski
    Intellectual 400 points

    Lee:

    Thank you again for your recommendations, I greatly appreciate it.  The DS250DF230 is a wonderful part, but my thoughts of the cross-point switch functionality cannot provide a loopback.  The 2x2 cross-point switch provides a 1-2 fanout or a A-B / B-A crossover per the figures below.  I hope I am wrong, but please comment.

  • 0 in reply to Sean Iwasaki
    TI__Mastermind 43795 points

    Hi,

    If the device is routed in the system to support upstream and downstream channels, the 1:2 function or the crossover function would perform a loopback.  Depending on the channel connections, the loopback could be implemented on either upstream or downstream signals.

    Regards,

    Lee

  • 0 in reply to Lee Sledjeski
    Intellectual 400 points

    Lee:

    Thank you for your recommendations again.  Unfortunately, our new product does not support routing to provide loopback.