The perfect buck or boost converter?

[eem2am]

Hello,

I am doing SMPS's for a single product which sometimes runs off a battery, and sometimes off the secondary rail of an offline converter.

So:

I am doing a Boost converter as follows:-

V(in) = 2.1V
V(out) = 27V
P(out) = 2W
Switching frequency = 100KHz
(I have a 5V power rail available to act as a bias supply)


Also, I will be doing a Buck converter as follows:-

V(in) = 30V
V(out) = 2.4V
P(out) = 0.4W
Switching frequency = 100KHz


Given the above specification, is the following circuit the perfect way to do both of these circuits (as a synchronous buck or boost converter)..................

Schematic: Synchronous Boost Converter:

https://i29.tinypic.com/2vdi23t.jpg

Schematic: Synchronous Buck Converter:

https://i32.tinypic.com/263ww7b.jpg


.......taken from page 8 of .............
**broken link removed**

It looks cheap, simple and highly efficient.

It seems just too perfect to be true

Is it really as good as it seems?
Can you see any bugs?