Cyclone V VCCIO increases when VCCPD is applied

[pvl]

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 : 5CEFA9F23I7N

[AqidAyman_Intel]

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]

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

[AqidAyman_Intel]

Hello,

Do you refer to the Pin Connection Guideline and Power Sequence documentation in your design?

You can refer here:

FPGA Documentation Index (intel.com)

10.4. Power-Up Sequence Recommendation for Cyclone® V Devices (intel.com)

Regards,

Aqid Ayman

[AqidAyman_Intel]

Hi,

We do not receive any response from you to the previous question/reply/answer that I have provided. Please update me if there is any new update from the solution given. If not, this thread will be transitioned to community support.

Thank you.