Lpc2000

Mmm.... I'd have to check it out. I'll probably try it this Monday. 
It looks nice because it uses very common components.

Guille

--- In lpc2000@yahoogroups.com, Sean <embeddedrelated@w...> wrote:
>
> 
> What type of efficiency does a linear regulator give you when setup 
in a 
> switching-style topology for low currents?
> 
> Check out L7805C datasheet figure 27 in case you don't know what 
I'm 
> talking about.
> 
> While we're on offtopic, what diodes do you guys recommend using, 
> especially for lithium backup purposes?  Most diodes that I see 
that are 
> frequently used have large forward voltage drops for any non-
trivial 
> current draw.
> 
> -- Sean
> 
> At 12:50 PM 12/2/2005, Guillermo Prandi wrote:
> >Thanks, Joel. Efficiency on those chips seems still very low 
(around
> >50% for my circuit's average load, 15 mA), though the low quiescent
> >current seems tempting.
> >
> >Guille
> >
> >--- In lpc2000@yahoogroups.com, "Joel Winarske" <joelw@i...> wrote:
> > >
> > > Guille wrote,
> > >
> > > > Hi! I am in trouble trying to find a voltage regulator 
suitable
> >for my
> > > > project; my project features an LPC2138, a GPS and a 
radiomodem.
> >When
> > > > idle, it draws around 20-25 mA from the 3.3V source, 500 mA 
when
> > > > working hard and with short (50 mS) peaks of up to 1.8A. The
> >supply is
> > > > a lead-acid 12V battery (can't change that), and occasionally,
> >when the
> > > > battery is charging, the input voltage will rise up to ~20V. 
The
> > > > problem is the regulator efficiency. We were going for the 
LM2676-
> >3.3V
> > > > switching regulator, because it seemed simple and in range, 
but
> >two
> > > > things made it a poor choice: it draws about 4.3 mA from the
> >battery
> > > > just for its own supply, and its efficiency when the load is 
in
> >the 20-
> > > > 25 mA range is awful (less than 50%, not counting 
Iquiescent). I
> >looked
> > > > everywhere but I couldn't find any other switcher with better
> > > > performance in these conditions (12V in, 3.3V out, 20-25 mA
> >average
> > > > load, but >1.5A capability). And there's a catch! The 
radiomodem
> >is
> > > > extremely sensitive to VCC getting lower than 3.3V especially 
in
> >the
> > > > current peaks! Also, it should be relatively easy to find in 
~400
> > > > quantities (i.e., Digikey, Mouser or your suggestion).
> > >
> > > I've used the MAX5035 for automotive apps.  Nice part.
> > > <http://www.maxim->http://www.maxim-
> >ic.com/solutions/automotive/parts.mvp/scpk/1458/pl_pk/0
> > >
> > > You might consider the MAX5090, it goes up to 2A.  The input
> >voltage range
> > > is 6.5V to 72V.
> > >
> > > Joel
> > >
> >
> >
> >
> >
> >
> >
> >
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