Embeded USB interface circuit in AV device for recording programs

A USB interface circuit achieving the purpose of shared tuner and recording function of AV device includes an AV signals conversion module, a power source module, a power source control module, an IR remote control receiving module, and a tuner/demodulator module;

• the AV signals conversion module is electrically connected to the USB controller to convert analog or digital AV signals into digital AV signals with a matching speed rate that can be identified by the USB controller;
• the power switch module is electrically connected to the USB controller to receive control signals from the USB controller;
• the power switch module is also electrically connected to the USB interface and a power source module in a TV set or a STB so to switch between two power sources that supply power to an IR remote control receiving module, the primary control module and the tuner/demodulator module in the TV set or the STB;
• the USB controller is respectively and electrically connected to the AV signals conversion module and the USB interface to receive digital AV signals converted from the AV signals conversion module and transmit those digital signals to the USB interface;
• the USB controller is further electrically connected to the IR remote control receiving module to receive remote control signals;
• the USB interface is electrically connected to the USB controller and the AV signals conversion module to supply power and provide a socket for connection by an external device.