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HD3SS3412: PCIe switch LVCMOS support

Benjamin Williams
Prodigy 30 points

Part Number: HD3SS3412
Other Parts Discussed in Thread: HD3SS6126

Hi, I'd like to know if the HD3SS3412 switch is able to switch LVCMOS voltage level signals (3.3V max). I see that the device is rated for differential inputs of -0.5V to 4.0V, but is typically used to switch PCIe signals in the range of 0 - 2V (common mode) and 1.8V (differential mode).

Will LVCMOS signals cause damage?

  • 0
    Guru 320550 points

    3.3 V LVCMOS is inside the absolute maximum ratings, so the device will not be damaged.

    But 3.3 V is outside the recommended operating conditions, so there is no guarantee that the device will work correctly.
    In particular, if there are only N-channel MOSFETs switches (which is likely for a high-bandwidth device), then voltages near the positive supply cannot go through.

  • 0 in reply to Clemens Ladisch
    Prodigy 30 points

    So in my application, I either need to pass PCIe gen 3.0 signals or LVCMOS. So at the 3.3V rating, I do not need to have the same bandwidth or dynamic response that the PCIe requires. Would the switching function still be operational for the 3.3V signals, allowing the LVCMOS signal to be passed through?

  • 0 in reply to Benjamin Williams
    TI__Guru**** 154540 points

    max 1.8v differential signal allowed to pass though for 3412. so 3.3v definitely not working.

    what's data rate of LVCMOS signal? maybe HD3SS6126 will work if LVCMOS is < 500Mhz

    regards

    brian