Clock Oscillators

Note: The clock oscillators are separate and not synchronous to the clock provided by the USB host interface.

In addition to the USB host interface clock, two fixed-frequency clock oscillators provide reference clocks for various FPGA components and systems.

  • Fabric / DDR4 Clock – This is a general-purpose 100 MHz clock for logic use. This clock should be used as the reference for designs using the DDR4 memory.
  • MGT Clock – This is an on-board reference for the gigabit transceiver quad on bank 225 refclk 0.

Refclocks for the three MGT quads (banks 224, 225, and 226) are also brought out to the expansion connectors. See the Pins List for connection details.

Pin Mappings

Fabric / DDR4100 MHzJ23 / J24 (Bank 66)
MGT125 MHzV7 / V6 (Bank 225)