> It's going to cost what it costs, but ceramic capacitors can have much wi=
der
> operating temperatures. =A010mJ at 16V is only 78uF. =A0You only need a f=
ew 20V
> ceramics in parallel to get that. =A0This is so obvious it's hard to
> understand what the problem is.

The existing design has 2200uF with a peak voltage of 16V, regulated
down to 3.3V
so (0.5 * (0.0022) * (16-3.6)^2) gives me 177mJ assuming the cap was
charged to 16V, but I have to deal with the low line case at 85VAC for
120V nominal and 162V for 230 nominal.  In the end, I have to run the
processor for at least 600mS beyond power removal, and the current
consumption number is somewhat vague... (You get a sense of what I'm
up against?)

Ceramics are also an issue in that they tend to crack with extremes in
temperature, but there are some that are specifically designed for
automotive and downhole use that I may be forced to use.

> These are rated from -55 to +85 degC, which
> should cover "outside in a metal box". =A0You'll have a hard time finding
> parts for the surrounding electronics to cover that range.

The joys of mushy specs.. So far, everything is ok there, even
crystals and semiconductors, but I don't know that 85C will actually
cover what we need.  I am pushing back to mgt on the mushy spec, but
that will likely just get tossed into my lap to solve.

--=20
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