# [EFM] Extended Temperature Optics

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All,
(forgive the wide distribution, but I'm sort of trawling for info...)

I've done a preliminary search on the origin of the fabled "-40 to +85 C"
temperature range.
This is what I've found.

Various semiconductor companies talk about these ranges.  Most often, they
are specified
as ambient temperature (Ta).  In cases where serious power is being
dissipated, a de-rating
curve or equation is supplied, and in some cases, certain air-flow rates are
suggested.  However,
there is a lot of inconsistency in the industry.  For example, Allegro says
the following:

Operating Temperature Range.
C =Commercial (0 °C to +70 °C)
S =Standard (-20 °C to +85 °C)
E =Extended automotive/industrial (-40 °C to +85 °C)
G =Extended industrial (-40 °C to +105 °C)
J =Extended industrial (-40 °C to +115 °C)
K =Industrial/military (-40 °C to +125 °C)
L =Automotive/military (-40 °C to +150 °C)
X =Special (i.e.,wafer probe at +25 °C only)

While National Semiconductor says:
In general, the temperature ranges are defined as follows:
Military: -55 to +125'C
Industrial -40 to +85'C (some variation, check datasheet)
Commercial 0 to +70'C
Automotive -40 to +125'C (some variation, check datasheet)
Note that in this case, even the specification indicates that it is not
definitive!

I found two standards that talk about temperature:

There is the Mil Spec: MIL-STD-883E 1012.1
This talks about either Case or Mounting surface temperature, and NOT
ambient.
(In fact, they give a diagram showing how you should build a liquid cooled
heat sink to
clamp the case temperature to the tested value.)  This document specifies a
wide range
of temperatures, including -55 to +85 and -55 to +125.  It seems the
military is
concerned about attacking cold places (Siberia?) as well as hot.

There is also JEDEC A105-B "Power and Temperature Cycling"
This talks about testing such that "the entire mass of each device under
test to reach
the specified temperature extremes".  This would seem to be a 'case'
temperature.
And, it requires the power to be turned on and off during the test (kind of
like a soak test).
However, this test is considered destructive and is for device
qualification.
Specifies temperature ranges of -40 to +85 and -40 to +125 C.

That is what I've found so far.  I can't say that this is very definitive,
and I looks to
me like the electronics industry has avoided this issue.  I invite anybody
who has
any other information to please contribute it to the group.

I'll save the rest of my comments for the optics exploder.
Regards,
Frank Effenberger

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