Although Apple is considered to be the originator of the elimination of the included charger, it has become the norm for smartphones not to come with a charger, so people have to buy their own. Due to the current cell phone battery capacity is getting bigger and bigger, coupled with people more and more the pursuit of shorter charging time, so high-power fast charger has become the first choice, especially gallium nitride GaN charger has become the mainstream, gallium nitride GaN charger output power is as high as 135W.

Early power adapters, usually by the traditional silicon steel or ferrite surround system primary and secondary coil transformer voltage, and then rectified and filtered to output the DC power we need, this power supply is also known as linear power supply. The figure below is one of the simplest linear power supply circuit diagram, not only only one way voltage output, and even the filter capacitors are not.

Linear power supply can be said to be simple and brutal, but the energy efficiency is low, want to increase the output power is bound to increase the volume and weight of the transformer, especially some high-power transformer, the volume often weighs several kilograms, but also brings a larger heat loss, which is obviously unacceptable to people, so now linear power supply is basically eliminated, and is only used in some audio amplifiers, and we use both cell phone Whether we use a cell phone charger or laptop power adapter, or desktop power supply, are used in the switching power supply.

Linear power supply energy efficiency is low because of the use of 220V 50Hz or 110V 60Hz frequency AC power, people found that if you mention the frequency of the input AC power supply, you can further enhance the efficiency of the power supply, which makes the transformer to ensure sufficient power output at the same time, but also to achieve a smaller size. But this will make the power supply circuit changes, switching power supply needs to be 220/110V 50/60Hz sine wave AC rectified into high-voltage DC, and then by the switching circuit will be inverted into ultra-high-frequency rate of the square-wave alternating current, and then through the transformer transformer, and finally rectified and filtered can be output to the DC we need, the following figure is a simple switching power supply circuit.

Then switching circuit how to turn DC into high-frequency alternating current? We have learned in high school physics, the primary coil of the transformer if the rapid current flow off, the secondary coil will also induce an alternating current, but the graph is a square wave rather than a sine wave. In the switching power supply, the semiconductor switching tube becomes the core component, it is through the high-speed switching to achieve for the transformer input power supply frequency enhancement, for example, ask our frequency AC is 50Hz, and the switching frequency of the switching tube to reach a few KHz, or even more than 1MHz. The higher the switching frequency of the switching tube, the energy efficiency of the power supply will also be improved, but due to the semiconductor components are also resistive, high-frequency operation when the heat is large, often to be fixed on the heat sink. We are currently commonly used to open the tube is mainly used in silicon-based power MOSFETs, but with the ever-increasing demand for faster switching speeds and lower resistance, silicon-based power MOSFETs have been pushed to the limit, so Gallium Nitride GaN semiconductors have become a new generation of power components.

Gallium nitride GaN is known as the third generation of semiconductors, known as the electronic performance to another higher level, to restore Moore's law of the rapid development of a new material, of course, obscure and difficult to understand the analysis of the material and the principle of operation we have skipped, we only need to know that Gallium Nitride GaN device electronic conduction efficiency of silicon-based devices is 1,000 times can be, Gallium Nitride GaN high electron mobility can be achieved higher Breakdown strength, faster switching speed, higher thermal conductivity and lower on-resistance, with gallium nitride GaN manufacture of high-efficiency power transistors and integrated circuits will be, to achieve higher power and smaller volume, such as the following chart is the silicon power components and gallium nitride GaN power components of the body type comparison, and the “5V1A” of the body type. Now the power can be done 30W.

Simply put, GaN GaN allows us to use a smaller body, higher efficiency and higher stability of the power supply. However, gallium nitride GaN power supply is good, but do not over-pursuing power when you buy, such as 100W or more can be powered for laptops, and cell phones and tablet PCs, choose 30W or 65W can be.