[time-nuts] CSAC change in temperature, max is now 40C

[brent evers]

My understanding is that 1000's of these are deployed on commercial ocean
bottom seismographs (Co. name not important) and per my last conversation
with them, that they had identified long term failure's on the CSAC.  They
also indicated that they could detect when failure was imminent, and that
microsemi was implementing a 'fix'.  Could be unrelated, but this might be
the fix.

Brent

On Mon, Feb 9, 2015 at 7:06 PM, Jim Lux <jimlux at earthlink.net> wrote:

> The latest rev of the CSAC data sheet (rev H) shows the max non-operating
> temperature to be 40C..
> and operating from -10 to +35C
>
> that's a substantial difference from the former version of the sheet which
> presumably had the temperatures from the summary page:
> The Quantum SA.45s Chip Scale Atomic Clock (CSAC) is available in the
> following versions:
>
>     Option 001, operates from -10 °C to +70 °C with an output frequency of
> 10 MHz, ADEV = 2.5E-10  (tau = 1 sec)
>     Option 002, operates from -40 °C to +85 °C with an output frequency of
> 10 MHz , ADEV = 2.5E-10  (tau=1 sec)
>     Option 003, operates from -10 °C to +70 °C with an output frequency of
> 16.384 MHz, ADEV = 2.5E-10  (tau = 1 sec)
>     Option 004, operates from -10 °C to +70 °C with an output frequency of
> 10.24 MHz, ADEV = 2.5E-10  (tau = 1 sec)
>     Option 006, operates from -10 °C to +70 °C with an output frequency of
> 5 MHz, ADEV = 2.5E-10  (tau = 1 sec)
>
>
> Rev H appears to be 121014  (12 October or 10 Dec 2014, I'd guess)
> http://www.microsemi.com/document-portal/doc_download/
> 133305-quantum-sa-45s-csac
>
>
> I wonder what happened?  Is it a typo? are they seeing high temperature
> failures?
>
> As a practical matter, a max operating temp of 35 and storage/ship of 40
> would make me nervous about shipping one in midsummer in California..
> That brown UPS truck gets pretty toasty warm, and 40C is easily achieved,
> although fairly unusual for "in the shade air temp"
>
> And, of course, makes it useless for outdoor applications of any kind.
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