At present, most of our common routers' built-in power adapters have AC output, and almost no DC output. So which one is more advantageous, AC or DC? Common AC power adapters (hereinafter referred to as AC power supplies) are usually accompanied by the symbol of AC, and DC power adapters (hereinafter referred to as DC power supplies) are DC. The inside of the AC adapter is mainly through the power transformer to complete the conversion and output, and the inside of the DC adapter is composed of a rectifier circuit.

At present, the common AC power adapter on the router has a copper core (wire package) inside. When working, the power consumption will be lost in the form of useless work, and the input voltage range of the line package power supply is very narrow, which cannot adapt to a variety of use environments. The common DC power supply is an adapter (such as a mobile phone power adapter, also known as a DC switching power supply), which is composed of a rectifier IC chip and a filter circuit, and the loss will be much lower.
The same 9V500mA output DC switching power supply and AC line pack power supply. It can be seen that under no-load conditions, the power loss of the DC power supply is only 0.49W, while the AC power supply has reached 1.59W. The difference between the two is 1.59-0.49=1.1W. The no-load loss of the AC power supply is 1.59/0.49=3.24 times that of the DC power supply! Connected to the tested wireless router, we can see that this gap continues to expand. The overall power consumption of the DC power supply plus the router is only 4.59W, and After the AC power is connected to the router, it reaches 6.06W. 6.06–4.59=1.47W. Compared to the unloaded 1.1W. And if the power consumption of the machine itself increases, this gap will continue to expand. It can be seen that, in the case of the same power, the DC switching power supply has the advantages of small size, light weight, low loss, and high power density. Especially the switching power supply itself has the functions of wide input voltage, high voltage stabilization accuracy, over-current and over-voltage, short-circuit protection, etc. It is precisely because of the above advantages that most of the current power adapter solutions for electronic products use DC switching power supply output.