GaN: Tracking fast-charging with ‘Lichi Law’
All forms of GaN fast charger are delivering an increase in output power of around 50 percent every 12 months.
BY XINKE LIU FROM SHENZHEN UNIVERSITY
The silicon industry is well-known for its laws. The most famous of these, attributed to Intel co-founder Gordon Moore, states that the number of components on an IC doubles every year. And also known to many is the law formulated by Robert Denard: as transistors are reduced in size, there’s no change in power density, as voltage and current scale with the length of the channel. Note, however, that since the mid-noughties, it appears that Dennard scaling has broken down.
There are also laws within the compound semiconductor industry. Maybe you have heard of Haitz’s law, which states that every decade the LED’s cost-per-lumen falls by a factor of ten, and that for a given wavelength, the light generated by a packaged device increases by a factor of 20. And more recently, thanks to the efforts of a Chinese collaboration that I am involved with, there’s ‘Lichi law’, describing the performance changes associated with GaN charging, named after the lychee trees that are near my laboratory at Shenzhen University.
Figure 1. (a) GaN fast-charging output power-product volume diagram. (b) GaN fast-charging output power-product quality diagram.
Over the last few years sales of GaN power devices have rocketed, following their adoption into consumer fast-charging products. Our collaboration has been delving into performance-related aspects of this, by conducting in-depth market research, and back in 2023 we identified the development laws at that time, leading us to propose Lichi law – it states that, on average, for every 12-month interval, the output power of commercial GaN fast chargers increases by about 50 percent. Two years on, we have found that consumer GaN fast charging is still following Lichi Law, and the industrial market is now enjoying similar dynamics.
To illustrate this rapid rise in output power, consider that back in 2018 the Anker GaN fast charger launched to market delivered just 30 W. While impressive at the time, a number of brands are now launching products with an output power of more than 300 W, and a power density exceeding 3.3 W cm-3.
Our work includes a survey for 3C certification data of GaN fast-charging products, which has enabled us to produce a visual comparison of the power parameter distribution of products listed in different years (see Figure 1).
Figure 2. Consumer GaN fast charging in recent years, evaluated in terms of (a) power density and (b) power.
Based on this data, one can see that fast-charging products before 2021 are predominantly concentrated below 1 W cm-3, with power density generally in the range 0.7-0.9 W cm-3, reflecting the state of maturity of early GaN technology. By 2023, most fast-charging products surpassed 1 W cm-3, with some even exceeding 2 W cm-3, which may be the industry’s first experimental high-density products. Fast-charging products are clustered in the 1-3 W cm-3 band from 2024 to 2025. So far, the maximum power density is 3.3 W cm-3, but a few products are appearing at around just 1.8 W cm-3, reflecting the technology stratification of the market – some vendors are pursuing the ultimate density, while others are focused on cost and stability.
Looking at the distribution of the mass of these chargers (see Figure 1 (b)), it is clear progress has been made. In 2018, when Anker introduced the first 30 W GaN fast charger, it had a mass of 54 g and a power density of only 0.53 W g-1. In 2022 OPPO broke new ground, with its 200 W GaN fast charger with a mass of 147 g and a power density of 1.36 W g-1 – this was the first fast charger to break through 200 W and have a power density of over 1 W g-1. Since then, Realme and Taigao have raised the bar, launching 240 W GaN fast chargers with power densities of 1.44 W g-1 and 1.37 W g-1 in 2024 and 2025, respectively.
We have also collected data on the maximum power and power density of GaN fast-charging products over time, and plotted power density growth (see Figure 2 (a)) and power growth (see Figure 2 (b)). These graphs show that power and power density rise over time with a rate of increase that’s highly consistent with the previously proposed ‘Lichi Law’ – that is, for every 12 months, the output power of commercial GaN fast-charging power units increases by about 50 percent.
Another observation is that GaN technology is accelerating its penetration from consumer-grade fast charging to industrial-grade power supplies, a trend that began in 2020. This finding has come out of conducting a comprehensive study, spanning 2018 to 2025, of consumer-grade fast charging and industrial-grade GaN power products (see Figure 3).
Figure 3. (a) Efficiency-power diagrams for industrial and consumer GaN
power supplies. (b) Power-volume diagram for industrial GaN power
supplies.
Compared to consumer-grade GaN fast-charging products, industrial-grade GaN power supplies are on average 4 percent higher, in terms of efficiency, and more than threefold higher, in terms of power output.
We have also determined that GaN has been more widely and deeply applied in the industrial sector, and its high-power, high-efficiency characteristics can be given full play in industrial scenarios, where it can fulfil demand for high-performance power supplies for industrial equipment.
Our extensive investigation of market dynamics has also identified a clear trend in increasing output powers. Between 2020 and 2021, we found that GaN technology was mainly verified in the initial stage of low and medium power scenarios. An example of this is Huawei’s launch of 3000 W products with the potential for power density improvement. Come 2022, GaNEXT launched 3600 W GaN server power supplies with a 20 percent increase in power over their predecessors, but still with lower volumes and efficiencies, due to packaging technology. At that time, the average power density of these industrial power supplies did not exceed 5 W cm-3, with sales predominantly oriented to lightweight scenarios, such as edge computing.
The last few years have seen significant progress. Since 2023, Navitas has made breakthroughs in GaN server power supplies, with power densities ranging from 5.88 W cm-3 for 3200 W products in 2023 to 13.79 W cm-3 for 4500 W modules in 2024, representing a 134 percent increase in volumetric efficiency in two years. At this point GaN technology began to be scaled for data centre applications, with an 8500 W prototype unveiled in 2024 with a 136 percent power increase from 2022, marking a breakthrough for GaN in medium-to-high power boundaries.
When deployed in industrial GaN power supplies, the power output density of GaN is generally within the range 3-6 W cm-3. Underscoring the outstanding advantages of GaN in industrial applications, that power output density is two-to-three times higher than that in consumer GaN fast charging.
Figure 4. GaN consumer-grade fast charging and industrial-grade power supply development.
Our comprehensive study of the evolution of GaN in power charging includes a review of peak power data of industrial GaN server power supplies, and parameters of consumer-grade products. This has enabled the construction of a power-year coordinate system, and a comparative chart of power evolution technology development between industrial and consumer fields (see Figure 4).
By undertaking a thorough analysis of this chart, we have observed the trajectory of GaN technology. Our data shows that the performance improvement for GaN power devices is highly consistent with ‘Lichi law’. Specifically, the output power of industrial-grade GaN power supplies increases by about 50 percent every 12 months.
We can conclude that through our study of consumer-grade GaN fast charging and industrial-grade GaN server power supplies, the output power of GaN fast charging tends to increase by about 50 percent every 12 months.
Contributors to Lichi’s Law include: Zhixiang Zhong, Yutong Wu, Bing Jiang and Hezhou Liu from Shenzhen University; Jingbo Li from Zhejiang University; Jinping Ao from Jiangnan University; Lixuan Chen from Unilumin Group Co., Ltd; Yuxi Wan and Daohua Zhang from Shenzhen Pinghu Laboratory; Zhanwu Yang from Red & Blue Microelectronics (Shanghai) Co; and Shengsen Chen from Cotell Intelligent Technology (Shenzhen) Co. Ltd.
