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Altera_Forum
Honored Contributor I
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VREFB1N0 and VREFB1N1 on a Cyclone IV E

Hello all, 

 

Just starting on a Cyclone IV E hardware design, and slowly making my way around all of the pins to ensure I have some idea what is going on. 

 

Bumped into pins VREFB1N0 and VREFB1N1. I understand why various I/O standards may need a reference voltage (and pin) but puzzled why (in this case) B1 needs two. 

 

Pretty sure that there is a simple answer, and that I just haven't found it yet digging through the reams of documentation. 

 

Comments appreciated. 

 

Thanks, Mark
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Altera_Forum
Honored Contributor I
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Nothing absolute in this answer - only Altera might be able to offer that... 

 

It's possible that the two pins, that you must supply with the same voltage, feed different parts of the device. This could be due to device fabrication constraints - perhaps a lack of available resource on a metalization layer. 

 

There's clearly no need for any reasons of current sharing... 

 

Whatever the reason you're not going to find anything in the documentation. All you can do is connect it up as required. 

 

Cheers, 

Alex
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