Some common rules
When the temperature is about 185 to 200°C (the exact value depends on the process), the increased leakage and reduced gain will make the silicon chip work unpredictably, and the accelerated spread of dopants will shorten the chip life to hundreds of hours, or in the best case, it may be only a few thousand hours. However, in some applications, the lower performance and shorter life impact of high temperatures on the chip can be accepted, such as drilling instrumentation applications, the chip often works in high temperature environments. However, if the temperature becomes higher, then the chip’s operating life may become too short to be used.
At very low temperatures, reduced carrier mobility eventually causes the chip to stop working, but certain circuits are able to operate normally at temperatures below 50K, even though the temperature is outside the nominal range.
Basic physical properties are not the only limiting factor
Design trade-off considerations may result in improved chip performance within a certain temperature range, but outside that temperature range the chip can fail. For example, the AD590 temperature sensor will work in liquid nitrogen if it is powered up and gradually cooled down, but it will not start up directly at 77K.
Performance optimization leads to more subtle effects
Commercial-grade chips have very good accuracy in the 0 to 70°C temperature range, but outside that temperature range, accuracy becomes poor. A military-grade product with the same chip is able to maintain slightly lower accuracy than a commercial-grade chip over a wide temperature range of -55 to +155°C because it uses a different trimming algorithm or even a slightly different circuit design. The difference between commercial-grade and military-grade standards is not only caused by different test protocols.
There are two other issues
The first issue: the characteristics of the packaging material, which may fail before the silicon fails.
The second issue: the effect of thermal shock. this characteristic of the AD590, which is able to operate at 77K even with slow cooling, does not mean that it will work equally well when suddenly placed in liquid nitrogen under higher transient thermodynamic applications.
The only way to use a chip outside its nominal temperature range is to test, test, and test again so that you can make sure you can understand the effect of non-standard temperatures on the behavior of several different batches of chips. Check all your assumptions. It is possible that the chip manufacturer will provide you with help on this, but it is also possible that they will not give any information on how the chip works outside the nominal temperature range.
Post time: Sep-13-2022