David E Arnold wrote:

> If you want high efficiency you might consider a switching regulator.
> There are versions available w/ low quiescient current and features
> like logic controlled shutdown, etc.  But they're more complex than
> LDO's and tend to use more space.

  And switching regulators are *not* LDO.

> But there's some quite simple ones such as the LTC1503-2 from Linear
> Technology, which requires no external inductors and just 4 small caps
> wired to it.

  Almost certainly not efficient.

> Disadvantage of an LDO is all the current must flow through the input;
> hence, they exhibit lower efficiency.

  Not exactly.  In LDOs, current flows into the reference leg, and is
thus wasted, *particularly* when exhibiting low drop-out.

  1} Low Drop-out
  2} Low reference current (efficient)
  3} Modest to substantial output.

  Pick any one of the above.

  You might *just* get away sometimes with two of the above.
--
  Cheers,
        Paul B.