Microphone (MIC) input circuit and vehicle-mounted system

Provided are a microphone (MIC) input circuit and a vehicle-mounted system. The MIC input circuit comprises an input circuit and a power source switch circuit, wherein, the power source switch circuit comprises a first end connected with an external power source, a second end connected with the input circuit and a control end used for inputting control signals to close or open the first end and the second end. The vehicle-mounted system comprises the MIC input circuit. The technical scheme is that on the basis of a traditional MIC input circuit, the power source switch circuit is added, and closing or opening of the power source switch circuit is controlled by a central processor. When the vehicle-mounted system works, the power source switch circuit is closed, and the external power source supplies power to the MIC input circuit at this time. When the vehicle-mounted system sleeps, the power source switch circuit is opened, and the external power source stops supplying power to the MIC input circuit at this time. Therefore, the problem of overlarge quiescent current of a whole vehicle caused by large leakage current of the MIC circuit is solved.