[amsat-bb] Re: Keep It Simple, MM
davegoncalves at gmail.com
Thu Oct 4 08:42:52 PDT 2007
> The other huge issue that is often not fully appreciated is the impact of
> radiation on modern components. As I'll show at the Symposium, the old
> familiar 14 and 16-pin plastic DIP devices were quite robust and could
> tolerate fairly high doses of radiation. This is not necessarily true
> anymore. This is why commercial and military payloads use rad-hardened,
> space-rated, and screened components. Commercial Off-The-Shelf (COTS)
> devices are manufactured for use in a benign environment where failures
> be corrected by replacement or repair.
However, because of the technology of some of the components, they will be
partially or totally immune.
To mind comes the Actel commercial line of FLASH FPGAs, billed as Neutron
Immune. Any good designer will have the REQUIRED rad hardness in mind with
designing the satellite electronics.
A Failure Modes, Effects and Criticality Analysis (FMECA) will point out the
points of the design which present the highest risk, to which one can design
controls to reduce the occurance (or detection and correction) of that
failure. Perhaps to mitigate a failure might you use a small section made of
older, but rad-hard parts. But the whole design?
SMT is here to stay, all the good modern parts are in SM packages, and logic
has already well passed the 14 DIP package stage (no more discrete logic
codestores). Unless we are flying into the Sun, or building a vintage
satellite, there is little good reason to use old parts in new designs.
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