On Wed, 27 May 1998 20:02:37 -0300, you wrote:

>Lads -
>
>After some due consideration and scouring of the microchip databook I have
>decided that I am going to re-design a PIC into my battery powered product
>and the current processor is getting heaved.  The wake-up on port b <7:4>
>and the super low current in sleep mode made up my mind - I'm looking at
>the 16C620 series as a likely candidate but the 16F84 could be used for
>much of the development without having to play the "wait to erase" game...
>
>The above having been proclaimed, I have a couple of questions that may
>sound trivial for those that have been designing with this processor
>already but I figure I'll pass them by in the interest of coming up the
>curve quicker -
>
>1) Is it just my mis-reading, but does the brown out enabled, turn the pic
>into a current HOG in sleep mode?  i.e. from 1uA to 300+uA?
Yes.  If you really want a brown-out, use a reset chip from Telcom,
Ricoh, Holtek etc. - they take about 1uA. For a battery powered app,
you probably don't need it. Power will always rise quickly when a
battery is inserted, and brownout will only happen when the battery is
dying, and you probably don't care too much then. 

>3) If I protect the electronics from a reverse battery with a diode right
>across the battery terminal, I will protect the electronics at the
>sacrifice of the batteries - this is ok - but - can a lithium coin cell
>source enough current to be of harm - i.e. heat, meltdown etc.?
No, but check the safety implications of doing this to the battery -
your customer may be upset if he gets burnt or the product melts after
incorrectly inserting batteries. 
A series schottky diode will only drop about 0.25V, and if you're
running on 6V anyway, this shouldn't hurt, and will reduce power drain
very slightly.



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