Hi,

For such a simple task, I would use a simple capacitive voltage doubler, driven by the µP clock output, i.e. and then use a linear regulator ( or a voltage ref ... or TL431 ).
using some MAX 630 ( a max 232 or ICL 7660 could also do it ... ) as a step-up converter is there somewhat overkill.
Max 761 ANs are to look at too ...

a convenient one had been the MAX 879 ... but production stopped !

Alain