>> Take at look at the micropower switcher design in the Art Of=20
>> Electronics
> for a fairly discrete solution.  Micropower switcher IC's are made=20
> by most
> of the larger semiconductor manufacturers such as Maxim, Linear=20
> Technology
> etc. e.g. an LT1615-1 works down to 1 volt, and consumes just 20uA=20
> when
> operating.  It also comes in a tiny package which means you could=20
> maybe even
> pack two supercaps into your PP3 housing.
>
> Could anyone please post this circuit somewhere? I live in Costa=20
> Rica and
> it=B4s VERY hard for me to get some of this books...


Google is (how come "EVERYONE" doesn't know this yet?) your friend.
Copyright violating copies of TAOE may not be available (and may) but=20
app notes for LT products surely are.

eg

Google hit #3
        http://www.linear.com/pc/productDetail.do?navId=3DH0,C1,C1003,C10=
42,C1035,P1774

#2    http://www.zetex.com/3.0/a1-7.asp

Datasheet with applications data galore (rebuild URL :-( ).

    http://linear-tech.com.cn/pc/downloadDocument.do;jsessionid=3DC4O6H5M=
2PTvOEEzzcDlXHmPb0LmR3fjRadKVgi1qs3JfOrUZzQbo!-848388738?navId=3DH0,C1,C1=
003,C1042,C1035,P1774,D3577

LT1615 is tiny - and stupidly expensive. $US1.80 in 5000 quantity.

For a cheap and cheerful low cost solution with less efficiency, less=20
cost and immense flexibility ask Google about MC34063


        RM=20

--=20
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