Electronics > FPGA

Help me understand the Gowin speed grade

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zapta:
Take for example the FPGA  LV9QN88PC6/I5, the ordering information mention speed grade 6 for commercial temperature range and speed grade 5 for commercial temperature range.



1. Does it means that if I use it for industrial temp range, the max clock speed I can use is lower than if I run it in commercial temperature range?

2. The Gowin IDE report the max clock speed of the design. Should I expect a lower max speed reported if I specify to the tools the industrial range?

We have a long thread in the link below about the meaning of C6/I5 and hasn't converge yet on a clear understanding. Any input would be useful.

ataradov:
I think the only meaningful way to interpret it is this:

The part number is for both speed grades at the same time and in the IDE you select the part number that includes both and the reported speed is for the part.  And this has to be the speed for the full (industrial) range.

The silicon performs worse in the extended temperature range, which is reflected in the number, but it is meaningless because your only option is to buy a "combined" part

It is kind of a bad way to specify this. It would be fine if the number actually meant something (like propagation delay or max clock speed in x100 MHz). And it might mean something internally, so the numbering makes sense to them. But externally it is just a number.

The only way to find out which part you need is to synthesize for all speed grades and see which part fits the constraints.

zapta:
@ataradov, the IDE allows you to specify if you plan to use for the commercial or industrial temp range and adjust the speed grade field accordingly (5 or 6).  You can see it the the dialog box in the attached page below.

With this in mind, I would expect that if I build for C (speed 6) or I (speed 5) I should get different max clock speed reports.



ataradov:
I did not see that window before. I looked at the usual places where other IDEs specify operating conditions and I could only see the bank voltage levels.

In that case their actual models may be tuned to the actual conditions, and the reported max clock should match set operating conditions.  But I would not expect significant difference. So, the maximum clock for C6 would be about the same as for I5. At the end of the day, it has to work in the same silicon.

gael:
Speed grade is how fast a device is.

COM/IND temperature range is over which temperature range the speed grade speed of a device applies.

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