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5,497 Views
Registered: ‎09-13-2011

Timing analysis at specific temperature

I am trying to run timing analysis for a Virtex 4 FPGA, with version 10.1 of the ISE software.  The FPGA that we are using is the industrial-grade, Pb-free XC4VSX55.  The model number is XC4VSX55-11-FFG1148I; however, the closest match that can be selected in ISE, (or specified in a makefile without getting an error message for invalid target package) is XC4VSX55-11-FF1148.  The problem that I’m having is that ISE ignores my temperature specifications of 95˚ C for the timing analysis, with the following error message:

 

WARNING:Par:237 - The temperature 95.000 Celsius is out of range, using default value.

Initializing temperature to 85.000 Celsius. (default - Range: 0.000 to 85.000 Celsius)

 

I believe the default temperature range is related to commercial/industrial-grade devices, but I have no way of specifying that I’m using an industrial-grade device.  I should also note that  the same exact makefile was used with ISE 9.2, and the timing analysis ran at 95˚ C. 

 

I would be grateful if anyone could suggest a way to get around this problem.  

 

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3 Replies
Scholar austin
Scholar
5,494 Views
Registered: ‎02-27-2008

Re: Timing analysis at specific temperature

david,

The problem is a non-problem. Your FAE has the answer (as I have seen and read the traffic on the internal Xilinx FAE newsgroup).

Simply stated, there is only one speeds file, for all parts. I grade and M grade parts are tested to meet that speeds file for their respective temperature ranges. For the static timing analysis, 85C means 125C for M, and 100C for I. Thus, the temperature is scaled to fit the file.

So, it really works, and is doing the right thing, even though you see commercial temperatures. If you desire 95C analysis, set the 85C 5% lower (so that you scale the 85C to match the 95C to 100C condition).



Austin Lesea
Principal Engineer
Xilinx San Jose
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Teacher rcingham
Teacher
5,488 Views
Registered: ‎09-09-2010

Re: Timing analysis at specific temperature

"Simply stated, there is only one speeds file, for all parts. I grade and M grade parts are tested to meet that speeds file for their respective temperature ranges. For the static timing analysis, 85C means 125C for M, and 100C for I. Thus, the temperature is scaled to fit the file."

UCK!

------------------------------------------
"If it don't work in simulation, it won't work on the board."
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Xilinx Employee
Xilinx Employee
5,211 Views
Registered: ‎07-31-2012

Re: Timing analysis at specific temperature

Hi 123Xilinx,

 

Glad to have you on xilinx forums.

 

At present there is no options to select Industrial Grade devices in ISE.

 

There is no need for an Industrial grade options in ISE, since the commercial device does analysis for the worst case. This worst case occurs at 85 degrees for commercial devices and 100 degrees for the industrial devices.

 

You can check this article for a better understanding and clarity  - http://www.xilinx.com/support/answers/4235.htm

 

 

Also observe that for commercial devices the temperature range which you can give in UCF is from 0 to 85 only. Even in the timing analyzer you have the range from 0 to 85 only. When you give a range out of this 0-85 the tool throws an out of range error.

 

Hope this helps. Let me know if it improved your understanding of the tool

 

 

Thanks,
Anirudh

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