Electronics > FPGA

A7-FTG256: Decoupling caps on unused banks

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rgc_:
Hi folks,

I have an A7-FTG256 based design in which every penny and mm2 of board is relevant. I managed to get the IOs under 100, so I can make them fit in two banks out of the 3.5 banks in the package.

The UG483 indicates how to maximize ESD protection in unused banks, and so I did. What is not specified, and I just assumed, is that I can remove also the decoupling caps for the unused banks from the design.

Is this OK? anyone have done that already?

Thanks in advance.

asmi:
Yes you can.

Also, if you want to shave a bit more off PCB area and cost, you might want to consider using Spartan-7 instead of Artix-7. They are available in smaller 15x15 mm 196 ball package which has 100 I/O balls, so it should be a better fit for your needs. S7 has a bit less of DSPs that equivalent A7, but otherwise they are pretty much the same (sans MGTs of course, but FTG256 package doesn't bond out any, so it's a wash).

rgc_:
Thanks asmi, much appreciated.

Thanks for the heads-up on the S7, too. Unluckily (and strangely) there's no S35 part, and the design wouldn't fit on an S25. That makes the A35 the less expensive part available for the project.

NorthGuy:

--- Quote from: rgc_ on November 24, 2021, 03:39:09 pm ---That makes the A35 the less expensive part available for the project.

--- End quote ---

How do you determine the price when it is not sold anywhere?

rgc_:
Distributors will usually give you a quotation, even when there's no stock. It is true that price ratio in between devices of the same family sometimes change, but I haven't seen too much of a change for the S7/A7 series in a few years, specially in high volumes where prices are nothing like in DK listings.

While that doesn't work for setting final product/contract pricings, it does work for picking up devices for new designs.

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