snip:
> 9V batteries typically aren't a good choice if you don't need
> 9V anywhere else in your circuit.

I've built an application that did need a higher voltage (the
Laipac RF modules I've just asked about) so I used a 9V.  I
powered the whole circuit directly from the 9V battery.  For
the PIC I used a 16HV540 which has built in voltage regulators.
Do these regulators have the same losses as a 7805?  My guess
is that they don't since my current consumption was low and I
calculated(?) a 5 year battery life.

The 16HV540 seems to be a unique chip.  With the built in
regulators there are also several features to lower voltages
during sleep, power the I/O ports, etc.  Are there any other
PICs or other MCUs that will take the high (9V+) supply voltages?

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