Hi Peter

The app. note on the Max630 describes such a supply, although it does use
two chips for the different functions. I've attached it to you only so as
not to clog the group. (550Kb)

I would suggest a switching reg for step up only, and use a simple linear
reg on the 12V side where you have lots of power and don't need the same
efficiency. So linear reg to 3.7V and the switcher stays off until needed.

Regards
Roland


At 02:29 PM 16/02/04 +1100, you wrote:
>Hi All,
>Might be stumbling down the wrong track, but worth investigating
>anyway...
>
>Can anyone recommend a switch mode regulator that will do boost
>and buck regulation?
>
>Basic usage is for a system that runs in a car, but requires
>backup battery. It also requires good 3.6V regulation.
>Current consumption at 3.6V is around 200ma max. backup battery
>is presently 3xAAA NiMh 650mA
>
>My idea is the battery can also be feed into the input of
>the switch mode so to maintain good regulation..
>
>Any help much appreciated as always :)
>
>Regards,
>Peter Mcalpine
>Sydney, Australia
>
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Regards
Roland Jollivet


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