Im talking about electronic devices, which may be handheld or similar, so nothing exposed to "artificial" temperature (welding, soldering, cooling with liquid gas). Devices designed to be operated by ("unprotected") humans, indoors or outdoors, such is the temperature range.
My question is: What are the especially temperature sensitive parts? I guess Im interested in the lower end (0°C and below). Are the batteries sensitive? What is also likey to fail when it gets too cold? – Which in turn also mean: which part must be kept warm if one has to attempt to operate such device in too cold a enviroment?
Example: I have recently bought a laser distance meassure, a UNI-T UT391A+. The specified operating temperature range: 0°C to 40°C. Many similar devices (even the UT391A, without +) specify -10°C or lower as their lowest. Why is that? The most obvious difference between UT391A+ and others is that the former has integrated bubble levels. Could that be what bumps the temperature tolerance by 10°?
Best Answer
Usually the semiconductors are the least temperature sensitive devices at low temperatures, a far as functionality goes. They may be rated for 0-70°C (commercial temperature range) but in fact many will operate fairly well down to liquid nitrogen temperatures (77K).
Capacitors (especially electrolytic and many ceramic types) will drop in value, sometimes precipitously or the internal resistance will increase greatly.
Batteries often perform very poorly at only moderately low temperatures- internal resistance increases and capacity shrinks. LCD displays can have problems with speed and temperature compensation.
Aside from the ceramic caps, some of which are just very temperature sensitive, most of these devices have liquid contained within them.
There is not a lot of reason to specify devices over a very wide range (and test them with margin to ensure that) if they are not going to be used in an automotive or military environment, and the testing and spec'ing allows the semi makers to segment the market and charge quite a bit more money for wide range devices. Many commercial semis will typically operate over a much wider range with relaxed specs- for example if you clock the chip at 250MHz rather than 300MHz.