Lpc2000

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-
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
>