[time-nuts] Lucent KS-24361, HP/Symmetricom Z3809A, Z3810A, Z3811A, Z3812...

Hal Murray hmurray at megapathdsl.net
Sun Nov 2 16:59:06 EST 2014

kb8tq at n1k.org said:
> The numbers quoted earlier (and they sound right) were 20 uA at 2.5V. That
> would be well under your 100uA. My *guess* is that self discharge / aging on
> a normal AA is going to limit things faster than a 20 uA drain.  

20 uA would last 15 years.  (assuming no self-discharge)

Self discharge is temperature dependent.  Graph here:
(poke the shelf-life button on the left)

At 20C, alkaline lose 20% in 10 years.  Or roughly 50 years for the whole 
thing.  (assuming linear and waving my hands)

> The UT+ data sheet from 1998 quotes an external backup supply of 2.5 to
> 5.35V with a drain of 5uA typical at 2.5 Volts. 

Ahhh.  That would be 60 years.  (assuming no self-discharge)  So it's roughly 
matching the self discharge rate.

kb8tq at n1k.org said:
> Your pair of AA’s will start off at 3.1V, but they will get to 2.5 long
> before they are truly dead. Is the RAM gone at 2.5000 or 2.4 or “about 2
> volts” …. 

The usual cutoff is 0.8 V.  It falls off quickly at the end.  It's still 50% 
at 1.25 V.  There is a graph at the above URL.

These are my opinions.  I hate spam.

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