Modern smartphones are more powerful than older desktop computers, so much so that you can open many apps and play AAA games. You can even use them as a desktop in the office with features like Samsung DeX. Even though playing a game on your phone may make it hotter than usual, it still dissipates heat effectively without the need for a fan. So how is this possible, given that they have become more and more powerful and smaller over the years?
Smartphones have a passive cooling system that directs heat away from the phone’s internal components and toward its surface, where it is expelled. It’s not perfect, but it works when the phone is used normally. Additionally, their components do not consume much energy, minimizing heat generation. When they get too hot, smartphones adopt secondary control measures that stop further heat generation until everything cools down.
These are some of the main reasons why smartphones don’t need fans on the same level as computers. On top of that, fans are bulky and consume a lot of power, which is not a practical or efficient design for a gadget meant to fit in your hand and be used throughout the day. Additionally, fans are mechanical parts that can’t handle the level of abuse we put our phones through (all those drops, bumps, and bumps) without eventually breaking.
Low power consumption and passive cooling
One of the main reasons phones don’t need a fan is because they use passive cooling systems that turn their surface into a large heat sink (an object that dissipates heat). Some phones, including flagship phones and gaming phones, use liquid cooling. One example is vapor chambers, which are tightly closed containers with a special coolant inside. Near the system-on-chip (SoC), which includes the GPU, processor, and memory (RAM), the liquid boils from the heat of these components, evaporating into a vapor that transfers the heat to the surface of the phone. It then condenses into liquid and then returns to the SoC to repeat the process over and over again.
Some phones dissipate heat using cooling materials such as graphite sheets and thermal paste that spread heat across the surface of the phone. Phones with larger cooling needs, like the Asus ROG Phone 9 and ROG Phone 9 Pro, use both vapor chambers and passive materials.
Another reason why phones do a better job of cooling is because the SoC doesn’t draw a lot of power, which makes sense since phones run on batteries. Essentially, the more voltage or current a component draws, the hotter it gets. For example, streaming a 4K video on YouTube or Netflix will place a higher load on these components, forcing them to draw more power from the battery to maintain performance. As a result, the phone heats up more and the battery drains faster.
Smartphones can protect themselves from excessive heat
If the primary cooling systems are not enough, the phone will switch to secondary security mechanisms. A common phenomenon is throttling, which reduces the processor’s clock speed (the speed at which it executes instructions). Throttling forces the processor to slow down, reducing the amount of voltage it consumes to minimize heat generation. This is why your phone becomes slow when it’s hot: the processor throttles itself so it can cool down.
One scenario that can force a phone to do this is when you play a game like “Call of Duty: Mobile” at maximum settings. Doing this while the phone is charging makes the problem worse. As already mentioned, the power required for high-load tasks already generates a lot of heat. Add to that the heat generated by the battery when it draws power from the outlet, and this bad charging habit is a recipe for overheating.
If these measures aren’t enough, you may receive a warning that your phone is overheating and needs to cool down. It can also shut down to protect its internal components from heat damage. However, for a phone to reach this point, it must be exposed to extreme heat, such as leaving it in direct sunlight, in a hot car, or under a pillow while charging. These measures also protect the lithium-ion battery. It can experience significant thermal degradation when subjected to temperatures outside its safe operating range. It also protects you, because an overheated phone can explode.
