About china AC-DC Power Supply
The power supply can be external, typically found in devices like laptops and phone chargers, or internal, such as in larger devices like desktop computers.
The power supply can be regulated or unregulated. In a regulated power supply, changes in the input voltage do not affect the output. On the other hand, in an unregulated power supply, the output depends on any change in the input. What all power supplies have in common is that they take power from the source at the input, convert it in some way, and deliver it to the load at the output. Input and output power can be alternating current (AC) or direct current (DC):
Direct current (DC) occurs when current flows in one constant direction. It usually comes from batteries, solar cells, or AC/DC converters. DC is the preferred power source type for electronic devices.
Alternating current (AC) occurs when an electrical current periodically reverses its direction. Alternating current is the method of supplying electricity to homes and businesses through power lines.
So if AC is the type of power supplied to your home and DC is the type of power you need to charge your phone, then you will need an AC/DC power supply to convert the AC voltage from the power grid to the DC needed to charge your phone battery Voltage.