Forum Discussion
New ContributorVREFB pin in Cyclone V
Hello,
Since it is mentioned in the Pin Connection Guideline that the pin needs to connect either GND or VCCIO if not used, then I am afraid you can't leave it floating.
Although I can't confirm with you that this is the cause of those faulty JTAG pins, I guess what will happen to the pin if left floating is the output of the buffer logic will be undefined since those pins are voltage-reference pins. It means that the pin should be connected to a valid logic for the hardware to work as expected.
Super ContributorHi,
you are right VREF pin of Cyclone V is dedicated pin without IO function, other Cyclone families have shared VREF and IO. Thus Cyclone V VREF hasn't pull-up feature and should be connected to GND or VCCIO when unused.
Sorry for causing confusion.
Regards
Frank
New ContributorThank you very much.
The reason I asked this question in the first place is that multiple boards have faulty JTAG pins (Bank3A), and I was trying to find the cause.
Is it possible for such a situation to occur if the VREFB3AN0 pin is used as an open?
Regards
