=20
> Ok, back to the actual problem at hand.
>=20
> I have an existing system using a 2200uF 16V aluminum electrolytic as
> energy storage, to keep a 3.3V processor running long enough to log
> some data after the AC input has been removed.  This works well enough
> in the existing product which is designed for in-home use, but I have
> been asked to redesign into an outdoor environment, and I will not be
> allowed to use anything other than minimal passive temperature
> control.  I am constrained by space and cost, but cost is moveable
> within reason, if I can justify the delta.  We don't have established
> environmental specs, which complicates things significantly.
>=20
> So, I am wondering what practical alternatives are available.  I
> haven't seen anything in supercaps yet that works for me, they are
> still relatively low voltage and high cost, though the capacitance
> values are impressive.

Hmm, in neither this or the previous post do you detail the regulator - so =
I will assume it is currently a linear one.

1. Using a switcher will give you more efficient use of the energy in the c=
ap, if you aren't already doing so.

2. I would be tempted to select some suitable capacitors that will store th=
e required energy over the required temperature range, but use a higher inp=
ut voltage if you can get suitable voltage rating capacitors.

3. can you use a switching pre-regulator to boost the voltage on the caps t=
o deal with the low line voltage condition, while maximising the energy sto=
red in the caps?

4. Is there some way that you can use  a 'supercap' on the 3v3 rail? This m=
ay allow you to achieve a larger energy storage at the critical voltage wit=
h minimal component count - but I don't know what the temp range of these t=
hings is.

5. Point out to your management that the temperature range they want you to=
 cover is going to require military grade components and hence the cost is =
going to rise dramatically .... ;)))))
--=20
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