Path: ...!feed.opticnetworks.net!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: Don Y Newsgroups: sci.electronics.design Subject: Re: Operating temperature derating Date: Thu, 13 Jun 2024 19:27:51 -0700 Organization: A noiseless patient Spider Lines: 147 Message-ID: References: <11n76jpt2qpaq49a6ka0qd8a82o8231o05@4ax.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Injection-Date: Fri, 14 Jun 2024 04:28:40 +0200 (CEST) Injection-Info: dont-email.me; posting-host="7d02a4da901d3695599f2605e9ce5b4c"; logging-data="2708944"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1+fVIxis74+mGGvBguGBGcW" User-Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.2.2 Cancel-Lock: sha1:5bfl0R32GwkElHjCHTUMYgS6zTc= In-Reply-To: Content-Language: en-US Bytes: 9154 On 6/13/2024 7:02 PM, KevinJ93 wrote: >>> I've never heard of lower level software being compromised at high >>> temperatures so basic phone calls would be ok but action video games would >>> run slower. >> >> The fact that the phone (and other exemplars) operates outside of its >> "operating range" confirms there is margin in the design.  We know that. > >> But, no one seems to know *what* this margin is.  (It's not just > phones but >> almost all consumer kit -- excepting those for which NO operating/storage >> conditions are specified!) >> >> This suggests that it is NOT a part of the design process but, rather, >> "whatever it is, it is". >> >> If I tried to make a call and the phone was 160F -- because it sat in my >> car for three hours in the sun -- would it work?  Is there ANYONE at Apple >> who could answer that question? > > 160F is 71C so the the circuitry I was involved with could be guaranteed to > work provided the internal temperature of the phone was not significantly > higher than that 160F. > > I believe similar limits would apply to other parts of the phone. > > However if the internal temperature had been raised significantly by any > internal power dissipation then all bets are off. > > CPUs are especially challenging as they can dissipate 5-10 Watts at extremes - > there is no room for anything in the way of heat sinks or fans etc. The best > they can do is to thermally couple them to the case. > > The power amplifiers in the RF section are also significant heat generating items. > > Your question has a multi-dimensional answer, it depends upon a host of other > things including the recent usage of the phone. Of course! And, I am just using phones as an example as they are ubiquitous. If you wander around your home, there are undoubtedly countless items that all have real limits on their operation -- yet DETERMINING those would be difficult (especially if you wanted to know REAL limits and not just PUBLISHED limits) > A phone could be designed to guarantee operation at the temperatures you state > but that phone would certainly cost more, be physically larger, heavier etc. > The current specifications have been accepted as adequate by the majority of > customers. Probably there do exist ones with extended environmental specs for > specialized applications such as the military where that is more important than > cost, weight, size etc. But that's exactly my point! The phone, AS DOCUMENTED, is considerably less capable than it is, in reality! If it adhered to its published specifications, I suspect a good many people would not use it -- because they routinely encounter conditions that exceed those published for the phone. SOMEONE (at Apple) knows this to be the case as they wouldn't market a product that had millions of users complaining that their phones stopped working in the summer (winter?) months. > If you want to improve the likelihood that your phone works when you need it - > don't leave it lying in sun. Even in a hot car some places are cooler than others. Of course. I've used this as an example of how WIDE the margin is in the phone's design (*my* phone isn't an iPhone). I doubt many people worry that the car interior may get too hot for their phones -- because most people have never had a phone refuse to operate due to temperature extremes! >>>> We expect cars to continue to operate in those temperatures.  What's the >>>> criteria that we use to determine what should and shouldn't be expected >>>> to remain operational? >>> >>> Automotive devices that expect to be in the engine compartment are designed >>> for -40C to +125C or +150C. >> >> The devices I mentioned are located in the *passenger* compartment. >> What value an engine compartment that can't be *controlled* by devices >> in the passenger compartment?  :> > > I've also worked in some aspects of automobile design and there were multiple > environmental zones defined - the cabin being the most benign. > > Probably parts there are specified to 105C. Although it can get pretty toasty > at the top of the dashboard. Dash gets up above 160. I've been amused that the ambient temperature sensor is so acurate -- yet "sees" the heat reflected off the (180F) pavement! Clearly some "engineering" at play, there. >> Will the GPS operate when the vehicle's interior reaches 160F?  What about >> the roadside assistance feature?  Backup camera?  Will the electronics that >> govern the cycling of the air conditioning compressor function?  Do you recall >> ever hearing someone complain of the electronics in their vehicles NOT working >> when they returned to their parked vehicle after work?  ("margin") > > The temperature is not uniform in the car and often electronics are placed in > areas where they won't reach the high temperatures you mention - in some of my > cars for example the electronics were under the seats or behind the glovebox. Yes, but over the course of an 8 hour "work day" (baking in the sun), I suspect there are no "refuges" in the vehicle's interior. If the air temperature is 113, then the car *will* climb to 113, over time. (It will *drop* to 90 degrees after 10PM, tonight -- and today was relatively cool -- just barely 100F) >> The fact that the car manufacturers recognized these some devices WOULD fail >> (and added a variety of idiot lights on the dash to signify those failures) >> suggests they either couldn't make them operate over these extremes *or* >> couldn't AFFORD to make them operate over these extremes. >> >> But, as a buyer looking to drop $50+K on a vehicle, what assurances do >> you have that those systems (for which you are paying additional monies) >> WILL operate when you are the vehicle's owner?  If they won't operate >> when the vehicle is sitting on the *dealer's* lot, will they operate when >> the vehicle is sitting in the grocery store's lot?  Your employer's lot? >> Your driveway?  On the highway?  (etc) > > Modern cars are impressively reliable but they may not be guaranteed to operate > over the full gamut of environmental conditions and usage. They just have meet > the great majority of the customers' expectations. If you are charging a premium for certain technology features, it seems like you would take steps to ensure that they *worked* in every market in which they were offered. As I said, I stepped behind the wheel of certain vehicles and watched failure indicators illuminate in rapid succession: "That's because the car is in the sun..." "Ah, OK. So, if I want those features, I should keep the car in the shade? How do I do that on the roadways?" >> Vendors seem to treat *consumers* as ignorant dweebs; the same sorts of >> hand-waving wouldn't be tolerated by an industrial/commercial customer! > > The market decides. Price is a dominant factor in vehicle sales. Price is a dominant factor in *many* decisions. Until performance problems capture headlines. I'm sure the airlines that bought Boeing products did so largely on price/performance/reputation issues... Consumers tend to be largely ignorant of product capabilities and limitations. They buy *features* -- without even guarantees that those features work! And, because they often don't understand what they have bought, they are never quite sure that a problem is "theirs" or the *device's*