立体声编解码器与扬声器驱动器WM8978

　　DESCRIPTION

　　The WM8978 is a low power， high quality stereo codec designed for portable applications such as Digital still camera or Digital Camcorder.

　　The device integrates preamps for stereo differential mics， and includes drivers for speakers， headphone and differential or stereo line output. External component requirements are reduced as no separate microphone or headphone amplifiers are required.

　　Advanced on-chip digital signal processing includes a 5-band equaliser， a mixed signal Automatic Level Control for the microphone or line input through the ADC as well as a purely digital limiter function for record or playback. Additional digital filtering options are available in the ADC path， to cater for application filtering such as ‘wind noise reduction’。

　　The WM8978 CODEC can operate as a master or a slave. An internal PLL can generate all required audio clocks for the Codec from common reference clock frequencies， such as 12MHz and 13MHz.

　　The WM8978 operates at analogue supply voltages from 2.5V to 3.3V， although the digital core can operate at voltages down to 1.62V to save power. The speaker outputs and OUT3/4 line outputs can run from a 5V supply if increased output power is required. Individual sections of the chip can also be powered down under software control.

　　wm8978是一个低功耗，高质量的立体声编解码器设计的便携式应用，如数码相机或数码摄像机。

　　该器件集成了立体声差分麦克风前置放大器，包括扬声器驱动器，耳机和差分或立体声输出。外部元件要求减少，因为不需要单独的麦克风或耳机放大器。

　　先进的片上数字信号处理包括一个5波段均衡器，用于麦克风或线路输入端通过ADC以及一个纯粹的记录或播放数字限制器功能混合信号自动电平控制。额外的数字过滤选项可在ADC路径，以满足应用程序过滤，如“风噪声减少”。

　　的wm8978编解码器可以作为一个船长或奴隶。An internal PLL can generate all required audio clocks for the Codec from common reference clock frequencies， such as 12MHz and 13MHz.

　　的wm8978运行的模拟电源电压为2.5V到3.3V，其数字内核可以在电压低至1.62V运作，以节省电力。该扬声器输出和OUT3 / 4线输出可以从一个5V电源，如果增加的输出功率是必需的。芯片的各个部分也可以在软件控制下断电。