The standard voltage of USB interface is 5V and the standard current is 500mA. In actual use, there may be errors due to various factors such as computer motherboard and power supply, but the maximum error cannot exceed +/-0.2V, that is, 4.8-5.2V.

USB devices mainly have the following advantages:

1. Hot plug. That is, when users use external devices, they don't need to turn off and turn on, but plug in USB directly when the computer is working.

2. Easy to carry. Most USB devices are small and light, which is very convenient for users to carry a lot of data with them. Of course, USB hard disk is the first choice.

3. Uniform standards. Everyone is familiar with hard disk with IDE interface, mouse and keyboard with serial port, printer and scanner with parallel port. But with USB, these application peripherals can be connected to the same standard personal computer, and then there are USB hard disk, USB mouse, USB printer and so on.

4. Multiple devices can be connected. USB often has multiple interfaces on personal computers, which can connect several devices at the same time. If a port with four ports is connected.

Universal serial bus

HUB, which can be reconnected; Four USB devices, and so on, as many connections as possible, all the devices in your home can be connected to a personal computer at the same time, without any problems (note: 127 devices can be connected at most.

Prepare).