Lpc2000

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