Multiplexing circuit and mobile terminal

A mobile terminal, comprising

• a central processing unit;
• an audio codec coupled to the central processing unit that is configured to decode an audio signal output by the central processing unit;
• an external interface comprising a D+ pin and a D− pin that are specified according to a Type-C interface protocol that is configured to be coupled to an external device;
• and
• a multiplexing circuit comprising:
• a first switch circuit comprising
• a first transistor having a first gate electrode, a first drain electrode, and a first source electrode, and
• a first constant voltage control circuit coupled to the first gate electrode and the first source electrode that is configured to
• receive a first voltage at the first gate electrode and
• load a right sound channel audio signal to the first gate electrode;
• a second switch circuit comprising
• a second transistor having a second gate electrode, a second drain electrode, and a second source electrode, and
• a second constant voltage control circuit that is coupled to the second gate electrode and the second source electrode and configured to
• receive the first voltage at the second gate electrode and
• load a left sound channel audio signal to the second gate electrode;
• a third switch circuit configured to receive a second voltage,
• a first signal transmission end coupled to the D+ pin, the first drain electrode, the first switch circuit, and the third switch circuit that is configured to receive the right sound channel audio signal from the first switch circuit under control of the first voltage;
• a second signal transmission end coupled to the D− pin, the second drain electrode, the second switch circuit, and the third switch circuit that is configured to receive a left sound channel audio signal from the second switch under control of the first voltage;
• a right sound channel transmission end coupled to the audio codec, the first source electrode, and the first switch circuit that is configured to provide the right sound channel audio signal after receiving the right sound channel audio signal from the audio codec;
• a left sound channel transmission end coupled to the audio codec, the second source electrode, and the second switch circuit that is configured to provide the left sound channel audio signal after receiving the left sound channel audio signal from the audio codec;
• a first output end coupled to the third switch circuit, wherein the third switch circuit is configured to provide a bidirectional connection between the first signal transmission end and the first output end under control of the second voltage and between the D+ pin and the central processing unit;
• and
• a second output end coupled to the third switch circuit, wherein the third switch circuit is configured to provide a bidirectional connection between the second signal transmission end and the second output end under control of the second voltage and between the D− pin and the central processing unit.