>> $US22 / 1

>That's not the one off chip price -- that's the price for Qty
> 1 of their PS demo board for the chip.

True - my mistake (reading too fast and/or uptoo late :-) ).

A better choice MAY be the LTC1624 controller

        http://www.linear.com/prod/datasheet.html?datasheet=395

Similar functionality but

    - Drives an N Channel FET
        (implements a high side pump for gate drive supply)

-    Wider input and output voltage ranges

    - Able to implement other topologies.

They use an external current sense resistor but it is in the high side and
drops only about 160 mV (AFAIR) so this is fairly bearable.

N Channel FETs are generally cheaper, more available, have better Rdson and
are available in higher voltage ratings (not an issue here).

All these small pinout modern chips tend to have lower functionality
compared with many existing "full house" switching regulator ICs with more
pins and therefore access to more functionality. Despite this they look very
useful for simple dedicated applications. Even some VERY old SMPS ICs (20 +
years)(eg xx384x family and many more) will implement many of these
functions with a little design work - external component count may be
higher. If you want absolute minimum parts count then finding an IC with
internal pass FET and flyback diode adequately rated for your application is
the "way to go". Cost MAY be higher.

        RM

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