In a message dated 97-07-29 18:19:34 EDT, you write:

<<
 My experience with the 16LC622 is that they cannot reliably be operated from
a
 3V lithium battery at 4MHZ.  (The data sheet claims that they will work down
to
 2V at a max clock of 40KHZ., but I needed a minimum clock of 4MZ.)  With a
4MHZ
 crystal some parts will not even startup with a fresh lithium battery (3.3V
to
 3.6 V).  My local FAE stated that the parts are speced at 4MHZ and 3.0 V.
 Other
 parts, will work fine at 2.4 V with a 4MHZ crystal.  I ended up using two 3V
 lithiums in series to get any sort of reliable operation from the 16LC622.
 Remember to test at the voltages you expect with a weak battery.  Good Luck.

 ----- Steve Miller >>
Hello Steve and all,
I did a project a while ago that was faced with the same problem.  I solved
it by using a MAX859 (I think that was the part#) Switching mode regulator.
 It accepts down to 1V in and provides 3.6 volts out at 50ma.  It is a 8 pin
SO8 package and all you need is a 47mh inductor (This was about a 1206 SMD).
The device had to be small because it is wrist worn by astronauts.  It also
has a battery low output that can be monitored by the PIC.  We used a 1600mah
lithium primary cell that was 1" X .7" X .4".  The device had to run for 5
days on a single battery.
Hope this helps
Dave Duley
V.P. DreiTek Inc.