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TUSB73x0 support of PCIe Separate Clock Architecture

Franz Sebastian Fries
Prodigy 95 points
Other Parts Discussed in Thread: TUSB7340, SN65LVPE501

Hi Guys,

currently I work on a TUSB7340 PCIe/USB 3.0 Interface. My Problem is that i cant transmit the differential clock signal over cable. Therefore I want to use the Seperate Clock Architecture/Mode of the PCIe Specifikation to clock both sides with a 100 Mhz Refclk (with 300ppm divergency) to avoid the transmition of the Refclock Signal of PCIe.

In the datasheets of the TUSB7340 IC i dont find that much information about this topic. In the "TUSB73x0 Board Design and Layout Guidelines" User Guide is mention that the IC is optimised for Common Clock Mode but there is not statement about Seperate Clock Mode. On the Internet i dont find any information about this topic.

Can you please give me a statement about the clock modes supports by the IC??

Kind Regards

Franz

  • 0
    TI__Guru* 76130 points

    Hello,

    There should be no problem using a separate clock as long as you meet the PCIe clock spec and the TUSB7340's power-up sequence.

    Regards.

  • 0 in reply to Elias Villegas M.
    Prodigy 95 points

    Hello,


    thanks for the fast reply. This means there should be no problem but it could be one. Have you experience about the cable lenght you can reach with seperate clock mode??


    Is it right that the TUSB7340 dont support Data Clocked Refclk Architecture??

    Is there any chip i can use for recovery the clock out of the data stream??

    A lot of questions but currently i find no answers. :)


    I take a look at the timing specs of pcie and the power-up sequence of the chip and i am very happy about your quick help!


    Regards.

  • 0 in reply to Franz Sebastian Fries
    TI__Guru* 76130 points

    Hello,

    Regarding the cable length: typically for PCIe applications a flat cable is used and it should be not longer than a few inches (5" max. probably). Longer than that you will likely need a re-driver. We have PCIe redrivers (SN65LVPE501)

    Data clocked architecture: do you mean a clock embedded on the data stream? If so, then no, the TUSB7340 does not support embedded clock.

    I don't know a part number of a clock recovery device. You may want to ask that on the clocks E2E forum ( http://e2e.ti.com/support/clocks/default.aspx )

    Regards.