Hi Alex,

I'm not suggesting that stuff doesn't use switching regulators, I'm just
suggesting a possible reason why we don't typically see 5V batteries to
cater to digital circuits. The reason given was that cell chemistry made it
difficult. My alternative reason is that many circuits require such a
narrow range of voltage for proper operation anyway that you would need
some kind of regulator. I.e., it's not that you can't get a 5V battery,
it's that you can't get a battery that stays close enough to 5V (say
between 4.5 and 5.5) for its whole useful life.

Sean

At 10:30 PM 3/12/2003 -0600, you wrote:
>
> >
> > Don't you think that more of the reason has to do with the
> > fact that many circuits require that the voltage not go much
> > below 5V, so that you would really need at least 6 V to start
> > with to ensure that it stays above 5 for the life of the battery?
> >
>
>OK, I will buy that.  But how are most consumer electronics designed?  I
>was planning on making something pretty small, using coin batteries.
>However, I just read that they are designed to run at tenths of
>milliamps, with short peaks to tens of milliamps.  Not too good for a
>PIC circuit.  So I could use AAA's, but I would need 4 to get 6V.  Or I
>could use a 9V, but they are pretty big.
>
>My PDA uses 2 AA's.  I don't think it is all 3V logic, so I am guessing
>it uses some kind of step-up regulator?
>
>Alex
>
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