Thanks for all the replies - some helpful stuff there..

I think I'm on the right track, just need to use a chip with lower output=20
resistance.
I'm liking the LT1611/7 option, as it looks like it's possible to get very=
=20
low output ripple with it (~1mV compared to ~50mV with charge pump=20
variants), so I wouldn't need to double/regulate the voltage, saving at=20
least 2 chips. Haven't looked at the prices yet though...
Think I will probably order a selection, take my time and prototype a few=20
options (should have done so in the first place as it needs to be done=20
properly - defeats the object to have a well designed circuit powered from =
a=20
badly designed supply..)=20


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