This is a traditional smps or buck regulator application.
At around 90% efficiency you can easily get say 10 watts out on TO220
devices with smallish heatsinks - enough for most PIC applications.

Lots of circuits and ics around - see eg the nice people at Linear
Technology who have vast quantities of app notes etc on their web
site. (www.linear.com/apps)

At this voltage you will probably need an external pass element.
I personally would like to see an isolated design at this voltage
level or an exceptionally trustable crow-bar circuit on the output.

While regulators using cpu based controllers are achievable the black
magic involved has already been well done by the IC manufacturers -
if you're not designing thousands then a dedicated IC is a better
choice.


regards

            Russell McMahon

From: Tjaart van der Walt <tjaart@WASP.CO.ZA>

WIL REEDER wrote:
>
> Hi
>
> I am working on a low power LCD video monitor for my weekend
getaway. Solar
> and wind power into 12v batteries. I would like to run this 6 volt
LCD
> monitor off 12v and avoid the losses of a linear regulator or the
inverter
> and wall wart. Lm2576A comes to mind but are not available onesies
in this
> town. I need about 5 watts.
> Has anyone made a switchmode regulator with a c/f84 or a c508?? I
probably
> could use a few of these around the claim and an adjustable model
would be
> a hot item.
> Any Ideas?
> Thanks

I also have a similar question for the SMPS guru's. I've
been asked to re-think a design where a PIC get its power
from a 100V-150V DC line. How the hell does one drop
around 90V DC without creating an oven? I don't want to
use light bulbs as it is a potentially dangerous device.