>I still like the idea of using a SMPS. As for simple SMPS controller,
>I think they are comparable to the price of 10F204 and saves you
>the cost of programming of 10F204. For example we have an old design
>using MC33063AD SO8 and it costs about US$0.3. It may even save you
>the external MOSFET Q5 and the associated driving circuits (R3, Q2, Q4,
>Q3, R2, R4 and C7)if your budget current consumption from 5.5V
>is less than 500mA (I think it should be the case since MCP1700
>can only deliver 250mA, unless you have other plan for the 5V5).

Well I guess it would be advisable to drive all those LEDs of the 5V5
supply, rather than the smoothed 5v or 3v3 if it gets dropped to that.

However to take it back a step, I do wonder just what the purpose of having
the linear regulator is. If one is looking for real smooth supplies for
analogue purposes then I would suggest that one would regulate this
separately anyway to keep the supply noise from the PIC out of the picture.
I cannot see any real advantage in not having the switcher give the 5V
direct. A pad to fit a resistor to pull the output down to 3V3 (or any
voltage from 5V down to 2v5) would then be easy, for those who want the
lower voltage for some reason.

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