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Is there any leakage issue between power supplies during Cyclone V power up?


We are using Cyclone V (5CGXFC5F6M11C6N) in our prototype board.

Observed that during power up, there is a leakage between power supplies of the FPGA device.

Please refer to the attachement.

The power supply sequence is as follows:

1.1V (VCC_FP_1V1) --> 3.3V (VCC_FP_3V3) --> 2.5V (VCC_FP_2V5)

However, there is an leakage when 1.1V is applied to FPGA.

Leakage level of 0.05 ~ 0.36V can be observed at 2.5V rails.

We have isolated the FPGA supplies from other system circuits and devices.

In fact, the whole board has only 1.1V supplied to FPGA. 

From datasheet Cyclone V has the hot-socketing feature that suppose to prevent this issue.

Please also see attached schematic for the FPGA supply connections.

Can Intel confirm this phenomena on the eval kit or reference design?

If this is valid, what is the root cause and countermeasure?


Thanks & Regards 

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Hello , I am extremely sorry , i really dont know how i miss your case .. is that specific to the only two boards ? or you are seeing all the board ? if the FPGA is removed are you getting (i.e) Power supply circuitry with open , are you getting 2.5V ? Apologize again for not responding :( Thank you , Regards, Sree
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