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pvl's avatar
pvl
Icon for New Contributor rankNew Contributor
3 years ago

Cyclone V VCCIO increases when VCCPD is applied

Hi, Our VCCIO is 1.25V and applied before VCCPD is applied When VCCPD (2.5V as requested by the datasheet) is applied VCCIO increases by 50mV Is this normal behaviour ? My device is : 5CEFA...
AqidAyman_Altera's avatar
AqidAyman_Altera
Icon for Regular Contributor rankRegular Contributor
3 years ago

Hello,


Thank you for reaching out to Intel FPGA Community.


For this situation, it can be to the power sharing issue. Would you mind to check if the VCCIO and VCCPD are sharing the same power supply or not?


If yes, then you may need to add the proper isolation filters between those power rails.


Regards,

Aqid Ayman


pvl's avatar
pvl
Icon for New Contributor rankNew Contributor
3 years ago

Hi,

Thanks for your reaction.

All supplies are originating from the same 5V (adapter). But 2 fully separated (adjustable)DC-DC converters (type = LT3021) are creating the 2.5 and the 1.25V. I would expect that applying the VCCPD should not have any influence on the VCCIO power rail...

Kind regards, Piet