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BrianSune_Froum's avatar
BrianSune_Froum
Icon for Contributor rankContributor
1 year ago
Solved

Cyclone V custom board VCCIO puzzling behavior

Dear Intel and all, I am working on Cyclone V soc 5CSEBA5U19C8N. There is a very puzzling VCCIO behavior. According to "Cyclone® V Device Family Pin Connection Guidelines PCG-01014-3.2". Any 3...
Board Debug
  • BrianSune_Froum's avatar
    BrianSune_Froum
    1 year ago

    There are new measured data.

    If I attached a simple 10k resistor to the 1.2V rail. it will drop back to normal 1.2 range.
    But the loaded /w 10k is still measuring 40mV higher than unloaded DCDC w/o the FPGA chip.
    So there are some leakage current inside the diode path? from VCCPD to VCCIO?

Farabi_Altera's avatar
Farabi_Altera
Icon for Regular Contributor rankRegular Contributor
1 year ago

Hello,


I am taking over this case from previous owner.


How many devices you see the similar behavior?

This could possibly caused by VCCPD to VCCIO leakage current.


Do you have any undriven IOs with weak pullups?

Please make sure no VCCIO rails unconnected/unused especially FMC slots.

Can use pulldown resistors to stabilize the voltage.


regards,

Farabi