原创 Hot components are good for extreme designs

Heat and thermal issues are significant factors for lots of designs, whether they are in relatively non-critical applications such as the home, or harsh ones such as under a car hood, or worse. Heat pushes key parameters out of spec, skews timing, shortens component lifetime, and even causes malfunctions, or outright failure. There's no need for me to go into further details of "why" for this audience.

So what to do? In many cases, you start with lower-power components which dissipate less heat as part of the solution. At the system level, adding more advanced passive and active mechanisms can also help, including fans, heat sinks, heat pipes, cold plates, and even liquid cooling.

But radiation, conduction, and convection techniques won't help when your surrounding temperature is way up there, and there's little or no place for that heat to go. Think of down-well boreholes, the automotive environment on hot days, or electronics in space facing the Sun. (A project manager once remarked to me, playing off the tagline from the movie Alien, "in space, no one can have any convection cooling.") Certainly, while extreme cold is also a problem, it is much easier to deal with, and can be solved with local heaters at the expense of system power consumption.

What remains, then, is to try to use components which are rated to stand the heat, even if they themselves dissipate very little themselves. While most "automotive qualified" silicon-based ICs are rated to +125°C operating and +150°C storage—which is pretty good—that is not good enough for those really, truly nasty applications.

That's' why I was impressed with two very different ICs recently announced, and a connector. Analog Devices says their AD8229 instrumentation amplifier (in amp) is the first to be guaranteed and specified to +210°C. The same day, and far from the "analog" world, Texas Instruments introduced a floating-point microcontroller, the C28-family Delfino SM320F28335-HT, also rated to +210°C. For interconnection, ITT Cannon announced what they call a Permanent Downhole Gauge connector which can withstand 10,000psi (70 x 10⁶ Pa) and +200°C.

Put these devices together with some sensors and passive components (there are more of those available for >200+°C than there are ICs, of course) and you have high-temperature tolerant system, or at least a chance at building one.

To me, extreme design—where low cost is not the top priority, where production volume is usually one or a few units, and where one or a few push-the-envelope performance requirements are absolutely essential—represents extraordinary and creative engineering that is far different than just "low cost". Certainly, low cost is also difficult, but it requires a different kind of creativity and cleverness, plus some very good purchasing agents and assembly operations.

Have you ever worked on, or had close knowledge of, an "extreme" system, whether for temperature, vibration, reliability/longevity, low-power operation, sheer performance, or other attributes? Were results achieved using many small steps, or one or two big ones? ?