Dr Skip wrote:
>
http://www.edn.com/article/512133-Use_an_optocoupler_to_make_a_simple_low_d=
ropout_regulator.php

Sortof cute, but probably not genuinely useful.

If you need low dropout, you probably need a reasonably accurate output
voltage.  Using LEDs as the reference isn't going to get you that.  That
could be fixed by using something like a TL431 to drive the LED, but that
will have a sharp threshold probably causing instability due to the slow
response.  To get quiescent current down to reasonable LDO range, they have
to make the gate resistor very high, making response time abysmal.

Real LDOs are small and cheap, so there isn't a problem to solve here.

As long as you take it as a interesting comment and something to think abou=
t
rather than to actually implement, I suppose there is some value to that we=
b
page.


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