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.

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　　wm8978是一個低功耗，高質(zhì)量的立體聲編解碼器設(shè)計的便攜式應(yīng)用，如數(shù)碼相機(jī)或數(shù)碼攝像機(jī)。

　　該器件集成了立體聲差分麥克風(fēng)前置放大器，包括揚(yáng)聲器驅(qū)動器，耳機(jī)和差分或立體聲輸出。外部元件要求減少，因為不需要單獨的麥克風(fēng)或耳機(jī)放大器。

　　先進(jìn)的片上數(shù)字信號處理包括一個5波段均衡器，用于麥克風(fēng)或線路輸入端通過ADC以及一個純粹的記錄或播放數(shù)字限制器功能混合信號自動電平控制。額外的數(shù)字過濾選項可在ADC路徑，以滿足應(yīng)用程序過濾，如“風(fēng)噪聲減少”。

　　的wm8978編解碼器可以作為一個船長或奴隸。An internal PLL can generate all required audio clocks for the Codec from common reference clock frequencies， such as 12MHz and 13MHz.

　　的wm8978運行的模擬電源電壓為2.5V到3.3V，其數(shù)字內(nèi)核可以在電壓低至1.62V運作，以節(jié)省電力。該揚(yáng)聲器輸出和OUT3 / 4線輸出可以從一個5V電源，如果增加的輸出功率是必需的。芯片的各個部分也可以在軟件控制下斷電。