>I'm learning what a switcher is and how can I use it in
>my design... The only thing I know about LDO is that they
>are low drop out, but I have no idea what that means exactly.

Someone else did give you the basics, but a bit more might help.

Originally the 78xx series linear regulators required about 3 volts minimum
across the regulator, to maintain the output voltage within specs. This
meant that a 5v output required a minimum of 8V input, and generally a bit
more for safety.

Then what have become known as LDO (for Low Drop Out) regulators were
introduced. These require a lower voltage drop across the regulator to
maintain the output voltage within spec, typically somewhere between 0.5V
and 1V, so now a 5V output requires somewhere between 5.5 and 6V input
minimum.

However for your use a switching regulator would seem to be an ideal way to
go because of the input voltage range you require, and the amount of heat
that the regulator will dissipate. You may like to look at the Linear
Technology LTC1574 which has 3.3V and 5V versions, with a maximum input
voltage of 16V. It requires only 2 capacitors and an inductor, for an output
current of 175mA in the reference design on the front page, but with
suitable component selection can go to 600mA. Also have a look at the
software that you can download from the LT site that helps you design the
regulator around their chips. If the input voltage is not high enough have a
look at some of their other chips.

http://www.linear-tech.com/index.jsp


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