I am trying to use the eval-ad7768fmcz with the UltraZed-EG PCIe carrier card with a Ultrazed-EG SOM connected. The FMC IO is connected to 1.8V high performance io.I was wondering if it is necessary to modify the evaluation board to run at 1.8V in order to get it to work.
I tried connecting the board with IOVDD=3.3V and I could see DCLK running, but as soon as I programmed the fpga, DCLK stopped. This led me to the assumption that the incorrect IO voltage was causing the issue. I then modded the board by changing SLP4 to position B to use an external IOVDD and shorted SL18 to connect IOVDD to DGREGCAP, although i am unsure if the latter was necessary since i am applying IOVDD=1.8V externally.
After the mod I measured DCLK to be toggling between 0-1.8V as expected, but I had the same result after programming the fpga and DCLK disappeared once again.
My main question is: Do I need to change IOVDD=1.8V to use the board with 1.8V fpga banks?
If the mods were necessary, were my mods correct?
I was unsure if changing slp4 to position B was needed if sl18 was shorted, because the DGREGCAP pin might supply the 1.8v, nixing the need for an external 1.8v supply.
However I tried measuring IOVDD with no external supply after sl18 was shorted and did not see 1.8v, so I used an external supply and this is when I could see 1.8v on IOVDD and measured the 1.8v DCLK.