What is LTPO Display and how does it save battery?

Jimmy Westenberg / Android Authority

High refresh rate displays have become commonplace over the past few years, even on budget smartphones. While a high refresh rate makes your smartphone feel faster and easier to use, it also comes with some major drawbacks – namely increased power draw and battery drain. Fortunately, the display industry has found a way to alleviate those problems with a new technology called LTPO, or low-temperature polycrystalline oxide.

So in this article, let’s find out how LTPOs work, what they do differently, and why you might want to introduce the technology to your next smartphone.

What is LTPO Display?

Google Pixel 6 Pro vs Apple iPhone 13 Pro Max Display

Eric Zeman / Android Authority

Before we talk about the features of LTPO, we have to first understand how traditional display panels work. Luckily, there isn’t much of it. OLED displays — or as Samsung calls them, AMOLED — are made up of three layers: an organic emitting layer, a protective glass surface, and a backplane that controls how each individual pixel behaves. The latter is where LTPO technology comes into play.

OLED backplanes are made of thin film transistors, or TFTs. Transistors are essentially small electronic components that provide logic to a circuit. The modern processors used in your smartphones and laptops pack billions of these transistors. Coming back to OLED displays, these transistors are responsible for two functions: turning individual pixels on or off and maintaining a set brightness level.

The display industry has gone through several TFT backplane implementations over the past decade, such as amorphous silicon (a-Si), low-temperature polycrystalline silicon (LTPS), and indium gallium zinc oxide (IGZO). Each of these techniques has its own strengths and weaknesses.

Until recently, most smartphone displays used LTPS or IGZO thin-film transistor technologies for their backplanes.

IGZO TFTs, in particular, offer high energy efficiency at the expense of display density due to their large size. In addition, they are somewhat more expensive than the LTPS TFTs that manufacturers have demonstrated for the past half-decade or so. However, the power savings are worth a second glance. IGZO TFTs are capable of driving OLED panels at extremely low refresh rates, think of one update per second or less. Needless to say, this is an extremely useful asset for devices that rely on a limited power source, such as a smartphone battery.

IGZO Display Tech Low Power Consumption Showcase

While you can build displays with an IGZO backplane, many in the industry have instead opted for a hybrid implementation called low-temperature polycrystalline oxide (LTPO). In simple words, LTPO is a combination of two existing display technologies: LTPS and IGZO.

The result is a display that can refresh at a wide range of refresh rates – from 1Hz to 120Hz and beyond, thus achieving true variable refresh rate (VRR). The LTPO can also achieve the higher pixel density that we expect from LTPS-based displays commonly found in today’s smartphones.

Performance Specs ExplainedWhat is Variable Refresh Rate (VRR)?

It is worth noting that Apple holds several patents related to LTPO displays. However, manufacturers have already worked around this by developing slightly different implementations to achieve the same end result. For example, Samsung says that its flagship smartphones use HOP displays—short for hybrid-oxide and polycrystalline silicon. It still offers the same functionality and efficiency benefits as the LTPO, which we’ll discuss in the following section.

What are the real-world benefits of LTPO displays?

Apple Watch Series 6 Always on Display

Jimmy Westenberg / Android Authority

Besides power efficiency, does having a variable refresh rate offer other benefits? After all, many smartphones already allow you to change the refresh rate manually. The answer is very simple – a true variable refresh rate implementation provides a lot more fine-grained control than two or three preset options.

While many devices have software features like adaptive refresh rates that switch between 60Hz and 120Hz, they are limited to these fixed levels. However, in many situations, you want your display to lock at a different refresh rate than either of those two options.

Take, for example, the always-on display feature on your smartphone, which by design displays static content for long periods of time. It doesn’t need to be refreshed 120 or 60 times every second. With variable refresh rate on the LTPO display, however, the software can decide to bring the refresh rate down to 10Hz or even 1Hz as needed.

See all: Android Smartphones with Best Battery Life

Another popular use case where LTPO can excel is in content consumption. Most movies are produced at 24fps, and playing them back on a 60Hz display may induce judgements or other motion-related artifacts. While software can compensate for this, it also isn’t very energy-efficient to run at a higher refresh rate than necessary.

LTPO can lower the refresh rate for static content, saving you power while using features like Always On Display.

The low refresh rate also means that the SoC of the device does not have to work as hard. In other words, the GPU will not consume additional power and will draw 60 or 120 new frames per second all the time. With an LTPO display, the device can refresh and aggressively reduce frame rates when you’re not touching the screen or playing back media. Most adaptive refresh rate implementations will only drop you 120Hz to 60Hz, because of the inherent inability of the display to go any lower.

Overall, the LTPO displays shine in use cases where you need a specific refresh rate, either for application or to conserve energy. The exact figures are not well publicized, but if estimates are to be believed, these displays are anywhere from 10 to 20% more efficient.

Which devices have LTPO displays today?

Android 12 beta 1 always displays without notification on lock screen

Jimmy Westenberg / Android Authority

The Apple Watch Series 4 was one of the first consumer devices to include an LTPO display in 2018. The power savings by adopting this technology allowed Apple to increase the size of the display and reduce battery capacity from last year’s model. While the move may seem counterintuitive on the surface, the increased efficiency of the display means users didn’t notice any real-world change in battery life.

LTPO displays are becoming increasingly common in the smartphone and smartwatch landscape.

Another thing to note is that LTPO TFT technology can also be used in LCD displays. For example, both versions of the Razer Phone include an IGZO-based LCD that can reach 120Hz. However, all VRR-sporting flagship smartphones released since then have stuck to an OLED panel with LTPO. Presumably, this is because most smartphone displays are manufactured by Samsung, while the only company to experiment with IGZO-based LCDs is Sharp.

Should your next smartphone have an LTPO display?

Google Pixel 6 and Pixel 6 Pro displays scattered on the table

Eric Zeman / Android Authority

The LTPO display, especially with the larger battery capacity, allows manufacturers to use the smartphone power budget for other purposes. This often results in devices able to pack in more power-hungry 5G modems and processing chips. So while you may not see a real-world increase in battery life compared to previous generations, you do get a more capable smartphone overall.

The efficiency gained from LTPO displays allows manufacturers to pack in more capable and power-hungry hardware.

As we mentioned earlier, it is likely that the LTPO display will make its way to mid-range smartphones as the technology matures. We have seen this happen in the past when a-Si TFT-based displays gave way to newer technologies like LTPS and IGZO.

Read more: AMOLED vs LCD: Everything you need to know

Until then, you can continue to rely on the adaptive refresh rate feature included in most of today’s smartphones. That said, LTPO is definitely a feature worth considering the next time it hits the market for a new feature.

Leave a reply:

Your email address will not be published.