HP82143A Powering a 41 _Extend Your HP41_

[Garth Wilson]

Every boost switching regulator I've worked with takes a pretty substantial amount of quiescent current (ie, with no load), which would drain the battery quickly.  You might be able to have it shut down when the calc is off; but I'm wondering if the lower (non-boosted) voltage will be enough to retain memory and keep the clock running, and whether the regulator can be brought up quickly enough when the calc is turned back on.  I really don't know.  The output capacitor could be big enough to keep the calc going for around five seconds, after which the regulator would have to be brought back up for perhaps a few milliseconds to charge it back up and then go back to sleep, if you could have a micropower timer handle that.