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LVDS input on PMOD connector

Former Member

Hi,

Is is possible to use the PMOD connectors to input LVDS Signals ?

As far as I understand, the C and D connectors don't have the 200 Ohm series resistors.
They are connected to a 3.3V Bank. But LVDS should be possible anyways, as long as one places the 100 Ohm termination externally.

Has anybody done this?

Thomas

  • 0

    Yes, you can input LVDS_25 signals on the PL Pmod connectors even when those PL banks are powered by 3.3V.  The Zynq-specific docs don't really state this clearly, but given the Zynq 7020 PL is 7-series fabric, you can also refer to the UG471, which states:

     

    It is acceptable to have differential inputs such as LVDS and LVDS_25 in I/O banks that are
    powered at voltage levels other than the nominal voltages required for the outputs of those
    standards (1.8V for LVDS outputs, and 2.5V for LVDS_25 outputs). However, these criteria
    must be met:
    • The optional internal differential termination is not used (DIFF_TERM = FALSE,
    which is the default value).
    • The differential signals at the input pins meet the VIN requirements in the
    Recommended Operating Conditions table of the specific device family data sheet.
    • The differential signals at the input pins meet the VIDIFF (min) requirements in the
    corresponding LVDS or LVDS_25 DC specifications tables of the specific device family
    data sheet.

     

    I haven't done this myself, but it appears to be theoretically possible.

    Bryan