The USB interface voltage is 5v 5% to provide external voltage. Does not represent a constant voltage of 5V. USB2.0 is smaller, with only 3% fluctuation. The current of USB interface is relatively constant, generally 500mA, while that of notebook is only 100mA.
The USB power supply voltage of +5v is the standard value, and some deviation is allowed. The power supply voltage of computer USB port is between 4.75-5.25v, which conforms to the specification of USB protocol. USB power supply current: +5v current, and the maximum value specified in USB protocol is 500mA, that is, the maximum output power of a single USB port is 2.5W.
The output voltage is DC 3.3V to 5 V; Output current: the current of USB 1. 1 is 500mA, and that of USB2.0 is 750mA.
For desktop computers, the voltage and current of the USB interface on the front panel of the chassis are lower than those on the back of the chassis. USB interface is an international standard, there is no difference. Output voltage refers to the voltage output by the commercial power after a series of measures such as UPS shaping, filtering and voltage stabilization, which is used by load equipment such as computers. This voltage is generally cleaner than the mains voltage and there is no impurity signal. Generally, the output AC voltage of UPS should be stable at 220V, without much deviation.