GPIB
GPIB
(OP)
This design requires a GPIB interface with an operating temp from -20 to 120 C. The issue is the current available GPIB do not meet this spec. Is there a way of designing one of these through VHDL on a FPGA? Does some one know any literature that can help me with this task.





RE: GPIB
The +120°C smells like a typo in the requirements.
RE: GPIB
RE: GPIB
Are you sure these requirements (or measurements) aren't in °F ? +120°F is just about +50°C, and that's a lot more reasonable.
RE: GPIB
RE: GPIB
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Both will run up to 55°C, and while they're not rated for -20°F, you might be able to demonstrate that they'll still work, provided the moisture environment is controlled.
TTFN
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RE: GPIB
RE: GPIB
According to him, TTL works just fine when it's glowing red.
I see 120C as a problem only for thermoplastic insulation and connectors.
Mike Halloran
Pembroke Pines, FL, USA
RE: GPIB
Additionally TTL's ΔTjc is relatively small. A 20°C or 30°C junction temperature rise in a CMOS part would severely degrade the MTBF.
TTFN
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RE: GPIB
My friend used TTL _because_ it survived _long_enough_ while operating _far_ outside its normal temperature range. There is no 'book' data from which to evaluate an application like that, and no warranties are offered or expected.
But 120C is not _that_ hot. Certainly MTBF, not specified here, will be shortened, so defensive measures like derating and disclaimers are advised.
I too think the OP spec may be a typo, but I can conjecture applications where it would be appropriate. I think that actually achieving it is more of a packaging materials selection challenge than an electronic design challenge.
No, let me rephrase that. I don't mean to minimize the challenge of actually meeting such a spec on the electronic side, but I do mean to suggest that it will be equally challenging and expensive to get the electronics into a package that will help it survive for a reasonable time, and to deal with the interconnect problems that appear.
Mike Halloran
Pembroke Pines, FL, USA
RE: GPIB
I agree this might be more work than it is worth but if it is an option I need to explore it. FPGA development. Is there a place where you can get a tutorial or state diagram for GPIB development.
RE: GPIB
Even if you have a 120°C rated FPGA, it's quite likely that none of your other peripheral components will be rated for 120°C.
The Arrhenius rate equation applies to expected MTBF. Assuming a 1 eV activation energy for a typical failure, a 100°C rise in ambient temperature will degrade the MTBF by a factor 5*10^-5, i.e., a 100,000 hr MTBF at RT will be about 4 hrs at a 120°. That's assuming there aren't physical-architectural limitations on either MTBF or performance.
One option is to find surplus MIL-STD-883 qualified components. They were all supposed to be fully functional at 125°C ambient temperatures.
TTFN
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RE: GPIB
TTFN
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RE: GPIB
http://en.wikipedia.org/wiki/IEEE-488
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