> Nice to see mchip is getting into low-cost, well-documented,
> easily-available analog type stuff. =A0That combination is hard to find.

Choose any 2.
I consider that cost level excessive.
If somebody would redo an MC34063 with up to 1 MHz operation and a
decent internal MOSFET in place of the non saturating darlington and
with otherwise similar functionality and price it should conquer the
world.  Start on 0.9V, run on 2V would be a bonus :-). Add optional
current trip sensing (switch source current sense) and a much lower
reference voltage would be good.

How hard can it be?
Hard, apparently.

An MC34063 can drive almost any topology (boost, buck, boost-buck,
Cuk, SEPIC, flyback, ...) , has a usefully capable internal switch ,
good voltage rating, and high side current sense. It lacks the various
soft starts and lockouts and more of many modern IC but you can do
most things with it with not too much effort at a fraction of the cost
of much more modern ICs. 100 kHz max is annoying. Darlington switch
makes efficincy poor at lower voltages. Update it and it would be
suitable for many more tasks than it is already.



     Russell McMahon

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