Everybody always talks about the massive computing power of smartphones (movies love the moon mission comparison) but still my phone rarely gets hot. (Only when I use it while charging sometimes)
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The processors in phones are very efficient, that’s one factor.
The design of the phone itself is a factor. A smartphone is thin, and a lot of heat is dissipated through the surface and screen of the phone. You may notice that if a smartphone is wrapped up in someways, it can get warm and slow itself down.
My Flip 3 gets hot (and goes into thermal control by stopping processes and eventually shutting down when running Android auto (as does a lot of people’s I hear) and all my phones have gotten very warm when playing some games on them.
They heat up because of the light traveling trough the circuits. The bigger they are the bigger the distance traveled the bigger the heat.
I think this is how they work
They dont use alot of power, so they dont make alot of heat. Any heat they do make gets lost threw the phone’s body with the surrounding air.
Try having your phone do something heavy and put it in your pocket for a while, it gets hot! Not alot of surrounding air in your pocket.
It’s helpful to understand where the heat is coming from. In electronics, energy is converted to work in the form of computation. This process isn’t 100% efficient though. Some portion of the energy is wasted. That waste energy comes in the form of heat energy.
Mobile electronics are designed to be incredibly efficient, and they draw less power to begin with. So the amount of waste heat energy generated is very small. It’s small enough that we can simply let it dissipate through the phone case.
You might also have heard about the growth of computing power. Your example of smartphones versus the Apollo mission computers is a great comparison. This increase in power is owed to the fact that we’re able to manufacture processors with increasingly smaller internal components. As the components get smaller, they require less total energy, but the density of their energy per square centimeter may still go up.
In recent years, the demand for mobile computing has driven an entirely new metric: computing power per watt of energy. Put simply, manufacturers like Samsung and Apple have a tremendous incentive to deliver A) a lot of computing power and B) long battery life, because that’s what consumers want.
So over the last couple of decades, massive amounts of research & development has gone into designing chips with lower energy consumption per unit of computing power. The result are chips that can do more work with far less energy than old computers. This means less waste heat.
My kids play Roblox on my phone, and I wish it would have a fan to cool! It was so hot the other day, it had to cool down before it could charge the battery. On second thought, perhaps it’s MY battery that needs replacing.
It’s a good question that others have answered well here. I’m surprised though that no one has mentioned the newer Apple MacBook Airs which don’t have a fan or any air vents and run fast relative to PCs from just a couple of years ago…
The first way chipsets can get rid of heat is simply getting hot, which heats the chassis, which dissipates the heat. The performance of phones is generally tuned to not generate more heat than the chassis can dissipate. They could crank up the performance, but then your phone would need a fan.
The new MacBook Air vs. MacBook Pro vs. Mac Mini are good examples. At certain price points they all have the same chipset, same GPUs and CPUs. The Air doesn’t have a fan, which makes it thinner and quieter. But this limits how fast the chipset can run and for how long. Really hit an Air hard with say video crunching, and it’ll soon throttle the performance of the chipset to keep the heat down because the chassis alone can’t dissipate heat fast enough.
The Pro can run that heavy load longer since it does have a fan, but it may eventually have to throttle too.
The Mini can do even better since it has a bigger fan, no throttling that I’ve heard of. But there’s a version of the Mini that can run Apple’s highest-performance chip, called the Studio. This looks like the Mini but it’s over twice as tall just to accommodate bigger heat sinks and two much bigger fans.
It’s all about balancing desired performance with the ability of the hardware to move the heat out. You just don’t need a fan at lower performance levels.
Many years ago CPUs were rather power hungry for the performance they provided. Remember, a CPU is basically a space heater that does work, so they put out a lot of heat. I remember my very old computer without a fan. It ran at about 2 MHz, but it would get warm after a while. We’ve done a lot to make CPUs much more power efficient, so we can get more and more work done while producing less heat.
For example, the first Apple-designed phone chip was the A4 13 years ago, and it put out 5W of heat. The newer A16 puts out 8W. That is more, but the phones are bigger so there’s a lot more phone chassis space available to dissipate that heat. And that’s at maximum running the two high-power high-performance cores. The A16 has four low-power cores, each of which puts out a small fraction of that heat, and each of which is much more powerful than the single core in the A4.
Electronics, particular integrated circuits like CPUs, produce heat. Dealing with heat is a big part of designing hardware – one of the many ways to combat heat is to use the right components, in the right way to lower the heat produced.
There’s passive heat sinks where no moving fans etc are needed – they often require some airflow meaning the case has to allow air to enter so the heat-sink can get rid of the heat. With some smart phones, the case is actually the heat-sink.
If the component produces more heat than a passive cooling can handle (or the passive element would have to be very large) active cooling like fans or water cooling is needed. You will have different things in your computer needing different levels of cooling – so finding a single solution for all of it isn’t always easy.
Quite a lot of computers, particular those you may not think of as a computer like your smart-watch, cell phone or even TV, uses passive cooling. There’s a ton of SBC (Single Board Computing) that also works perfectly fine with passive cooling – ie. no fans. Characteristics of those kind of computers is that they’re not designed for speed, but for efficiency and hence low heat generation. For one, running a fan on a battery wears the battery out in no time – but generally less heat means smaller components and smaller products.
Which brings you to your gaming computer or data center computer, where power/max-performance is important. In many cases they may even be “over clocked” producing even more heat than they were designed for. Very effective cooling is required or they will burn/melt in no time and losing a $1000+ computer in a few minutes due to overheating is not exactly fun (or cheap).
Looks like my phone is smarter than I am, it knows when to cool down before it gets too hot!
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