UPGRADE YOUR BROWSER

We have detected your current browser version is not the latest one. Xilinx.com uses the latest web technologies to bring you the best online experience possible. Please upgrade to a Xilinx.com supported browser:Chrome, Firefox, Internet Explorer 11, Safari. Thank you!

Reply
Observer
Posts: 30
Registered: ‎10-12-2016
Accepted Solution

What is the use of speed grade and how can i identify it on custom boards having fan on it ?

 

Accepted Solutions
Moderator
Posts: 8,401
Registered: ‎02-27-2008

Re: What is the use of speed grade and how can i identify it on custom boards having fan on it ?

[ Edited ]

Further,

 

When you manufacture tens of millions of devices, naturally occurring variation will result in some devices being slow, other typical (as designed), and some faster.  These are graded into bins, and marked.  The test patterns all test to a specific grade before shipment.

 

When the bitstream is created, the tools know what speed grade they are intended for (you tell them).  If timing is met, that grade, or faster, will be required to get a working design on your board.

 

As noted, the device marking is the only valid way to confirm speed grade.

 

The fan must be removed to confirm.  Or, you could call your authorized Xilinx distributor, and ask them what they shipped to you.

 

 

 

Austin Lesea
Principal Engineer
Xilinx San Jose

View solution in original post


All Replies
Voyager
Posts: 1,440
Registered: ‎06-24-2013

Re: What is the use of speed grade and how can i identify it on custom boards having fan on it ?

Hey @ssampath,

 

What is the use of speed grade ...

The speed grade decides how fast your FPGA can work reliably

 

how can i identify it on custom boards having fan on it?

You really can't. The speed grade is not something encoded in Xilinx FPGAs it's just a marking on the package.

 

Hope this clarifies,

Herbert

-------------- Yes, I do this for fun!
Moderator
Posts: 8,401
Registered: ‎02-27-2008

Re: What is the use of speed grade and how can i identify it on custom boards having fan on it ?

[ Edited ]

Further,

 

When you manufacture tens of millions of devices, naturally occurring variation will result in some devices being slow, other typical (as designed), and some faster.  These are graded into bins, and marked.  The test patterns all test to a specific grade before shipment.

 

When the bitstream is created, the tools know what speed grade they are intended for (you tell them).  If timing is met, that grade, or faster, will be required to get a working design on your board.

 

As noted, the device marking is the only valid way to confirm speed grade.

 

The fan must be removed to confirm.  Or, you could call your authorized Xilinx distributor, and ask them what they shipped to you.

 

 

 

Austin Lesea
Principal Engineer
Xilinx San Jose
Highlighted
Voyager
Posts: 1,440
Registered: ‎06-24-2013

Re: What is the use of speed grade and how can i identify it on custom boards having fan on it ?

@austin are they always marked according to the test results or does it also depend on the demand?

 

What I mean is, could you end up with a slow speed grade marked device which actually passed a much faster speed grade during testing? (which would make sense to me :)

 

@ssampath in theory, you could run similar speed grade tests on your FPGA fabric and see what passes and what fails and from that, conclude the speed grade without removing the fan ...

 

Thanks,

Herbert

-------------- Yes, I do this for fun!
Scholar
Posts: 892
Registered: ‎09-16-2009

Re: What is the use of speed grade and how can i identify it on custom boards having fan on it ?

Herbert,

 

That's not very realistic.  Xilinx guaranty's the speed grade of the parts as marked.  How they decide the speed grade is very likely quite proprietary, and not going to be made public. 

 

Coming up with some kind of home-grown test to "up" your speed grade is just well,  ill-conceived, IMHO.  Better option would be to STA the part you have (if you don't know the speed grade because of the fan/heat sink, then assume worst case). 

 

Anything else, and you're rolling the dice; which all of us probably do occasionally for "test" builds. i.e. sometimes when I'm inserting test / chipscope logic I won't try hard to close timing.  I might bring something to the bench missing timing with some negative slack.  But that's only for short bench tests, never for release to customers..

 

Regards,

 

Mark

Moderator
Posts: 8,401
Registered: ‎02-27-2008

Re: What is the use of speed grade and how can i identify it on custom boards having fan on it ?

[ Edited ]

Yes,

 

If we need slow parts to fill orders, they may all be one or two grades faster in reality.

 

We only warrant what we sell, as marked, so you may be lucky, or not.  Hence why you need to meet the timing for the part we deliver to you (that is a guarantee, and is what you are paying for).

 

Are you unable to make a phone call to discover what devices shipped to you?

Austin Lesea
Principal Engineer
Xilinx San Jose
Observer
Posts: 30
Registered: ‎10-12-2016

Re: What is the use of speed grade and how can i identify it on custom boards having fan on it ?

thank you so much .

Observer
Posts: 30
Registered: ‎10-12-2016

Re: What is the use of speed grade and how can i identify it on custom boards having fan on it ?

thank you so much .