The iPhone 12 will likely be the first 5G phone for many. While that may be exciting, the challenge is that the faster data speeds of 5G come at the cost of reduced battery life.

This may come as no surprise to those who can remember the early days of 4G LTE phones, but Apple's first ever 5G iPhone does not hold a charge as long on 5G as it does when set to 4G. iPhone 12 and iPhone 12 Pro, on both network types Battery tests showed a difference of 2 hours, or about 20%, in run time when streaming web pages endlessly.

Fortunately, Apple has devised a solution to mitigate this. The concept behind this feature is simple: if the iPhone 12 does not need 5G, it will drop to LTE to conserve energy. Smart Data Mode is enabled by default, but can be turned off at any time from the iPhone's phone settings menu.

But how does the iPhone determine when 5G is needed and when LTE is sufficient? The criterion is actually very simple (in most cases): you are actively using your phone.

If you go to sleep with the display off, running regular updates in the background, or streaming music, Smart Data mode is activated and you fall into LTE. However, when it wakes up from sleep again and scrolls through social media, browses the web, or watches a video, the iPhone will allow 5G communication.

On its website, Apple offers another example of a situation where Smart Data Mode allows 5G. This suggests that there are scenarios where the iPhone 12 will use 5G instead of LTE, even when it is in sleep mode.

Now, again, if this sounds like a reasonable compromise to you, you don't have to lift a finger. Smart Data mode is enabled by default. However, if you find that your iPhone is slowing you down more than you would like, the fix is easy.

Go to the Settings app on your iPhone and tap Cellular, then Cellular Data Options, and finally Voice and Data. Here you can turn off Smart Data mode by selecting 5G On instead of the default 5G Auto. Also, if you want to disable 5G altogether, select LTE.

This is because we can envision a scenario where iPhone 12 users find that their apps and games are not downloading as fast as they would like and wonder how much benefit 5G is really providing. Understanding what Smart Data Mode is designed to do and how it works can help clear up that confusion.