Modern Car Digital Audio Systems

With the rapid development of automotive industry and microprocessor technology, embedded system has been widely used in automotive electronics. According to the multi-mission of automotive audio requirement, we design a digital audio system solution for the later automotive market.Firstly, the thesis analyze the background and development of automotive with the application of embedded system, introduce a development procedure of digital audio system . the whole system consists of six modules such as radio receive module , digital audio decode module , digital audio processing module , digital audio output module and system power management module, MCU module . the radio receive module use two leaf dice tuner from NXP to receive FM and AM broadcasting , which can successful remove the Muti-path noise; DAB4.2 and IBOC module are used to receive digital broadcasting . digital audio decode module is based on microprocessor TMP92 and audio decode IC TC94A92 which are both from Toshiba , this solution not only can decode mostly audio format such as MP3, WMA, AAC, but also can take control of the iPOD playing with better HMI operation . Digital Audio processing module is designed with the NXP DSP SAF7741 which can support multi channel analog and digital audio input such as DVD, SD card ,blue tooth and digital audio broadcasting , this solution can provide better Sound Effects such as SRS, Dolby5. 1 can only been felt in home sound system. Digital audio output is designed with TI Class D amplifier TAS5414, can perform large power and high quality audio output. System power management module used the TI multi channel output DC-DC power supply IC TAS43331 with a new CAN controller , successfully reduce the whole system's power dissipation and quiescent current .MCU Module used the NEC850 replace the TMS470 series to get the lower cost and lower quiescent current.The thesis originates from enterprise's actual project with an aim to give a reference for the development of digital audio system. The design to control the iPOD playing , new technology for CAN circuit design for reducing quiescent current and the first application of class D amplifier in Car audio system field are innovations in this thesis . The audio system design iPOD circuit with an iPOD authentication IC 2.0B , can take control the iPOD playing and display the music and movie information in iPOD disk to HMI. The new design for CAN IC can remove the 5V memory power, reduce the quiescent current to 7uA to meet the requirement of total 150uA for the whole system. The Class D amplifier is just applied in commercial product before, our system first apply it to car audio system with the small space and rough EMC impact , and reach the automotive level audio output performance .