[comp.sys.nsc.32k] How does the Dallas Semiconductor chip retain the time?

jkh@meepmeep.pcs.com (Jordan K. Hubbard) (05/29/91)

Not having any specs on my chip (I got it from Steve Liggett), I was
wondering..

I figure it either has a very small lithium-type battery someplace
(in which case I wonder about its lifetime), or a small nuclear
reactor of the Pons & Fleischman (or Fleischman/Pons, for our english
readers) type.  If it's the latter, how often do I need to sprinkle
it with heavy water?

I suppose it might also be a sliver of plutonium and a miniature
thermocouple, but that's REALLY farfetched!

:-) :-) :-) for the sarcasm impaired.

					Jordan

george@wombat.bungi.COM (George Scolaro) (05/29/91)

[In the message entitled "How does the Dallas Semiconductor chip retain the time?" on May 27, 15:27, Jordan K. Hubbard writes:]
> 
> Not having any specs on my chip (I got it from Steve Liggett), I was
> wondering..
> 

It does use a lithium battery. As per most lithium batteries that are drained
at leakage current levels, the lifetime is a nominal 10 years. Either that or
it has a non-volatile time offset which it then applies to the time value it
obtains from WWV (US standard time transmissions) via its tiny radio
receiver :-)

P.S. Congrats on fixing your broken traces...

best regards,

-- 
George Scolaro
george@wombat.bungi.com                [37 20 51 N / 122 03 07 W]

-- 
Dave Rand
{pyramid|mips|bct|vsi1}!daver!dlr	Internet: dlr@daver.bungi.com

maniac@vector.dallas.tx.us (06/01/91)

> Not having any specs on my chip (I got it from Steve Liggett), I was
> wondering..
> 
> I figure it either has a very small lithium-type battery someplace
> (in which case I wonder about its lifetime), or a small nuclear
> reactor of the Pons & Fleischman (or Fleischman/Pons, for our english
> readers) type.  If it's the latter, how often do I need to sprinkle
> it with heavy water?
> 
> I suppose it might also be a sliver of plutonium and a miniature
> thermocouple, but that's REALLY farfetched!
 
Actually, it's a combination of the two.  It does need a drop of water
every hundred thousand years, and it has a thermocouple around a mini
plasma fusion generator, underneath a bunch of insulation, which just
BARELY fits in the case/socket.

(Actually it is a small lithium battery, life is rated at 10+ years.  The
reason I know all this, is a) I have one in my pc532.  b) my company makes
them [Dallas Semiconductor is an interesting place, and vector is just a
name for the network impared 8-(] and c) I just spent a LONG time trying
to get one to work with a serial ported sram controller chip (DS1280))

> :-) :-) :-) for the sarcasm impaired.

(smilies, SMILIES, we don' need no stinkin' smilies!...)

-- 
Jon Buller       jonb@vector.dallas.tx.us       ..!texsun!vector!jonb
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