“Fast charging” is nothing more than a fast charger. In a sense, it is mainly used to make up for the shortcomings of the slightly slow progress of charging technology. Since it is impossible to improve the battery life by significantly increasing the battery capacity within the existing volume, it is possible to enhance the battery life of the phone by speeding up the charging speed of the phone. For example, OPPO’s creative slogan “Charge for five minutes, talk for two hours” can well illustrate the joy brought by fast charging.

At present, fast charging usually exists together with “gallium nitride”. Why can gallium nitride take on this important task?

For example, common digital products, such as smartphones and tablets, generally require DC power below a certain amount, but the current national unified rated voltage is 220V, so we must convert the 220V AC power delivered from the power plant to the home into a suitable DC power. At this time, a transformer or charger is needed for conversion, and no digital product is an exception. Obviously, power conversion technology is indispensable in our daily life. In the power conversion system, the most critical part is the power semiconductor component, and its performance will determine the quality of the power conversion system.

In order to make good power semiconductor components, it is necessary to use suitable semiconductor materials. At present, the most common semiconductor material is Si, but after decades of development and application, the potential of Si has been basically maximized and it is impossible to improve its performance. This is one of the reasons why gallium nitride (GaN) has gradually emerged.

Advantages of GaN

Take a good look at the most basic characteristics of gallium nitride. Compared with silicon, gallium nitride GaN has a large bandgap, a large critical breakdown electric field, a high saturated electron drift velocity, and stable chemical properties. The main reasons why it has been favored by the fast charging industry are as follows:

1. Excellent thermal performance. Due to the performance limitations of silicon devices, auxiliary passive heat dissipation (To package or heat sink) is often required in medium and high power applications, which is one of the main reasons for the increase in the size of switching power supplies. GaN devices are far superior to increasingly outdated power MOSFET devices in terms of performance, with lower on-resistance, lower capacitance, higher current and excellent thermal performance. This excellent feature allows GaN power devices to basically completely get rid of traditional auxiliary passive heat dissipation methods and rely on small-scale methods such as PCB copper cladding and via tin plating to achieve heat dissipation. Abandoning the bulky auxiliary passive heat dissipation facilities, the volume can be made smaller.

2. GaN’s high frequency characteristics bring high efficiency. Generally speaking, to improve the power density of switching power supply products (that is, the higher the output power under the same volume), the first thing to focus on is to further increase the switching frequency, which can effectively reduce the volume of transformers, filter inductors, and capacitors, and the material performance of GaN can just meet this requirement.

In general, gallium nitride (GaN) components have the characteristics of low on-resistance, fast switching speed, high temperature resistance, and good voltage resistance. They have advantages that silicon components do not have and are indeed particularly suitable for use in power conversion systems.