USB interface multiplex circuit, mobile terminal and earphone

The invention provides a universal serial bus (USB) interface multiplex circuit, a mobile terminal and an earphone. A USB connector is simultaneously multiplexed to support an audio function and a data transmission function, so that the number of peripheral interfaces can be effectively reduced; a processor is utilized to detect signals of the USB connector, and determines whether the USB connector is inserted by a peripheral according to the detection signal; and when the processor determines that the USB connector is inserted by the peripheral, the processor detects voltage value of an audio circuit, and determines the type of the peripheral inserted into the USB connector according to the detected voltage value. By multiplexing the USB connector and determining the type of the peripheral inserted into the USB connector according to the detected voltage value of the audio circuit, reduction of the number of the interfaces in the mobile terminal and judgment of the type of the peripheral can be realized, and