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PCIe Ref.Clock Switch

Bahram Afghani
Prodigy 75 points
Part Number: TMUX136

Hi TI team,

Application: 2:1 analog switch on PCIe Ref.Clock

Requirement: Switch additive Jitter: sub Psec

off isolation and xtalk : -40 dB and higher

Please recommend a part that closely meets the above requirement.

PCIe ref. clock is HCSL mode, 350mV DC offset with a swing of 100mV to 700mV; depending on channel insertion loss.

HCSL termination implements, 50ohms to GND, does a direct connection (No AC coupling) cover the fail safe requirements?

Thanks,

Bahram

  • 0
    TI__Intellectual 1066 points

    Hi Bahram,

    TMUX136 should be a good suggestion based on your requirements. But TI also has passive multiplexers specifically designed around PCIe switching applications. See our product selection page here 

    Thanks,

    Stephen 

  • 0 in reply to Stephen Scheramic
    Prodigy 75 points

    Hi Stephen,

    I am muxing the PCIe Reference clock, not the PCIe signals. Frequency is fixed 100MHz.

    First question: Do floating inputs on TMUX136 cause any oscillation?

    Second question: The part will be powered by 3.3V, the common port will be muxed (only once) between the PCIe_REF_CLK_P line and a 3.3V CMOS signal. Assuming that PCIe_REF_CLK_P has a DC offset of  < 1V and a swing of 1V is TMUX136 a safe part to use?

    Thanks,

    Bahram

  • 0 in reply to Bahram Afghani
    TI__Intellectual 1066 points

    Hi Bahram,

    Floating inputs shouldn't cause any oscillation except that if they are truly floating they could pick up noise from the environment which may couple into the active channels. That is why we recommend a pull down resistor on any un used channels, but it is not a requirement. 

    As long as the switch inputs do not exceed 3.6V, that application should be fine. 

    Thanks

    Stephen