I've put this circuit together based on the data sheet for the chip
Would be most grateful for cririque from them as understands this stuff
Eagle files attached
cheers
Mike
booster.sch (97.8 KB)
booster.brd (28.5 KB)
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I presume that's the manufacturer's recommended circuit - the layout would benefit from a ground plane - if you are limited to single-sided board that's potentially an issue, I would at least run a continuous ground trace around the edge of the board to provide some approximation to ground plane.
@MarkT
thanks
there will be a ground plane on both sides (double-sided board)
left them out as it makes it easier to see what's going on 
I would say that its important to choose suitable inductor, and follow the advice in datasheet about the capacitor ESR ratings... Keeping the layout tight reduces all the stray inductance and capacitances which is always good thing with switch-mode.
indeedy will do
thanks
Mike
It looks like you only have 3 places for connections, 12v, GND, 5v. Why not have extra 5V and GND connections, they might be handy later.
cyclegadget:
It looks like you only have 3 places for connections, 12v, GND, 5v. Why not have extra 5V and GND connections, they might be handy later.
it's part of a bigger project, so that's all I need