----- Original Message ----- 
From: "Jinx" <joecolquitt@clear.net.nz>
To: "Microcontroller discussion list - Public." <piclist@mit.edu>
Sent: Tuesday, March 29, 2005 1:30 AM
Subject: Re: [PIC:] High sleep current on 16F88


> > > Sleeping 12F675 is ~10nA
> >
> > 10nA huh, that's pretty small
>
> The ones I've tried are actually 6nA

How do you measure that?

> > > long-term stability than anything with a 32k xtal like an RTC chip
> >
> > I don't understand, what does it use for the timebase if not a xtal?
>
> They do use a crystal - must be factory-trimmed or compensated
> or something. Probably around a minute or so per year accurate.

I've been running a 1307 with a 32k crystal (on a solderless breadboard
no less) and it's keeping great time.  After two weeks it's still within
a couple of seconds of where I set it.  It didn't seem that accurate at
first, but after I grounded the case of the tiny crystal, this seemed to
really make a difference.

AIUI, if you're having trouble with them running fast then noise is the
most likely culprit.

> Which implies overall stability of  0.00002% or tuning a 32.768kHz
> crystal to within 0.00655Hz and keeping it there

Shouldn't that be .0002%  ;-)

> BTW, I've dropped a "please enlighten me" email to Microchip
> about the F88 errata

This should be interesting.  I wonder how long it will take them to
respond?

-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist