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Daveb · Guest

Hi

We're looking at using an FPGA in a land based mission critical
application (not life critical). The latest generation of devices with
their huge resources are very tempting but the feeling is to stay with
older technology particularly with their larger geometries and higher
core voltages. With regard to the low voltages, a well designed PCB
with clean supplies and a low impedance/inductance ground should reduce
ground bounce, etc. to an acceptable level. Has anyone had bad
experiences or have views regarding the use of these latest FPGA
(and/or MCUs) devices in such applications ?

Thanks
Dave

Peter Alfke · Guest

Daveb, your question indicates your suspicion that modern ICs ( like
FPGAs) offer less reliable system solutions than the older technology.
That suspicion is not shared by the (admittedly biased) IC industry,
nor by the user community which accepts the newer technologies and
higher capabilities gladly (even while they complain about the usual
teething problems).
You have to put more care (and knowledge) in your pc-board design, you
have to pay more attention to signal integrity between ICs, but you get
so much more capabilities that you can afford to think about
self-checking or redundant designs that increase your reliability.
If your suspicion were justified, it would be the kiss of death for
progress as we are accustomed to expect...
Peter Alfke, Xilinx Applications

Daveb · Guest

Peter,
I should have made myself clearer. By older technology I meant 'older'
FPGA technology e.g Spartan-II with a 2.5V core voltage. I'm not
suspicous of the newer devices' reliability, just keen to see what the
consensus is regarding the ever reducing core voltage (i.e. reduced
noice margins) & reliability of system implementations.

Dave

Peter Alfke · Guest

Daveb, that's exactly what I was addressing.
If you decouple Vccint well, and use the right multi-layer board for
good Vcc distribution, there should be no FPGA-internal problem. You
can still use 3.3-V I/O, even on the newest devices. We have made sure
that the I/O can be 3.3-V capable and tolerant, even though that has
increased our chip size and thus the cost.
People build extremely reliable complex systems with the modern
devices.
We used to point to the Mars Rover, which used the then most-modern
Virtex devices to control its wheel movement (and other functions). If
NASA was willing to use the most modern technology for such a risky and
high-visibilty and publicity project, you might also want to do that...
Peter Alfke

Daveb · Guest

Thanks Peter. I wonder what devices the Mars Beagle2 Lander used :)

Aurelian Lazarut · Guest

Daveb wrote:

David Belohrad · Guest

Peter Alfke wrote:

Austin Lesea · Guest

David,

Our latest Virtex 4 is 600% less likely to be upset by soft errors.

http://www.xilinx.com/xlnx/xweb/xil_tx_display.jsp?sGlobalNavPick=&sSecondaryNavPick=&category=&iLanguageID=1&multPartNum=1&sTechX_ID=al_v4rse

or

http://tinyurl.com/clzqh

As well, its total dose resistance has also increased (improved).

Your intuition is incorrect: the more advanced technologies are
improving their ability to withstand the effects of cosmic rays, and
radiation.

There may have been intermediate products that were designed poorly (by
other manufacturers), but that is no reason to avoid the latest
technology when it is properly executed (by everyone else).

Austin

Austin Lesea · Guest

Dave,

If you are concerned about "reliability", then I would assume you are
concerned about gate oxide lifetime, hot carrier injection (HCI),
negative temperature bias instability (NBTI), electromigration (EM), and
so on.

All of these are detailed in our process qualifications which ensure
that every device we sell meets the generally accepted commercial (and
industrial) lifetimes of better than 20 years.

In fact the latest 90nm triple oxide reliability results are as good, if
not better, that the previous technology nodes.

http://www.xilinx.com/bvdocs/userguides/ug116.pdf

(see page 20)

Austin

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