Spartan® Family FPGAs

[sjg69]

Hi all,

So I have a shiny new SP605 and the XM105 to go with it. I'm in the process of designing a video/audio-capture card, and will be debugging it on the XM105 before making an FMC variant. 

I was wondering about the voltage robustness of the S6's pins. I know they're running at 2.5v on the FMC card, so does that mean I need to put QuickSwitches (or similar) in place in-between my 3.3v logic on the expansion card and the connection to the FPGA ?

Normally I'd assume so, but I read "somewhere" last night (sorry, new baby, which means lots of extra time for reading the web while feeding/rocking-the newborn-to-sleep (iPad's are great!), but very little actual sleep...) that the S6 would be ok if a 3.3v signal was presented as an input on the expansion lines... Driving 2.5v will be fine (anything above 2v will count as logic-high) but I don't want to blow up the nice new card before I really get any use out of it!

Thanks

  Simon

[jschimek · Accepted solution]

I'm worried I'm missing some nuances with this question, so I'll make a generic statement.

Spartan-6 inputs, regardless of bank voltage can safely receive 3.3v signals.

Check out the Vin spec in the data sheet:

http://www.xilinx.com/support/documentation/data_sheets/ds162.pdf

As far as I'm aware the XM105 is just creating a short to the FPGA.

Regards,

Jon

[sjg69]

Nope - no nuances. I'm rarely accused of being subtle [grin]

Thanks for that - I did in fact have table-2 in ds162 open in front of me, but somehow I missed the "All i/o standards" part of the description... I'll get rid of the Quickswitches then :)

Cheers!

  Simon.