原标题：Maxim MAX9888立体声音频CODEC解决方案

　　Maxim 公司的MAX9888是采用FLEXSOUND技术的全特性立体声音频CODEC，具有高性能和低功耗特性，特别适合用于手提设备。D类放大器为两个扬声器提供高效而低辐射的放大(每路950mW)，不需要滤波器。集成的旁路开关可在D类放大器不使用时可使放大器直接连接到传感器。MAX9888 具有立体声DirectDrive耳机放大器和差分接收放大器，双路I2S/PCM/TDM 数字音频接口。本文介绍了MAX9888主要特性，简化方框图和功能方框图，以及麦克风输入，线输入，ADC输入混合器，录音通路信号处理，数字信号路由，数字带通滤波，扬声器放大器信号和处理处理等方框图以及采用模拟麦克风输入和旁路开关与数字麦克风输入和接收放大器的典型应用电路图。

　　Stereo Audio CODEC with FLEXSOUND Technology

　　The MAX9888 is a full-featured audio CODEC whose high performance and low power consumption make it ideal for portable applications.

　　Class D speaker amplifiers provide efficient amplification for two speakers. Low radiated emissions enable completely filterless operation. Integrated bypass switches optionally connect an external amplifier to the transducer when the Class D amplifiers are disabled.

　　DirectDrive® headphone amplifiers provide a true ground-referenced output, eliminating the need for large DC-blocking capacitors. 1.8V headphone operation ensures low power consumption. The device also includes a differential receiver amplifier.

　　Three differential analog microphone inputs are available as well as support for two PDM digital microphones. Integrated switches allow microphone signals to be routed out to external devices. Two flexible single-ended or differential line inputs may be connected to an FM radio or other sources.

　　Integrated FLEXSOUNDK technology improves loudspeaker performance by optimizing the signal level and frequency response while limiting the maximum distortion and power at the output to prevent speaker damage.

　　Automatic gain control (AGC) and a noise gate optimize the signal level of microphone input signals to make best use of the ADC dynamic range. The device is fully specified over the -40NC to +85NC extended temperature range.

　　MAX9888主要特性：

　　100dB DR Stereo DAC (8kHz < fS < 96kHz)

　　91dB DR Stereo ADC (8kHz < fS < 96kHz)

　　Stereo Low EMI Class D Amplifiers 950mW/Channel (8I, VSPKVDD_ = 4.2V)

　　Stereo DirectDrive Headphone Amplifiers

　　Differential Receiver Amplifier

　　2 Stereo Single-Ended/Mono Differential Line Inputs

　　3 Differential Microphone Inputs

　　FLEXSOUND Technology

　　5-Band Parametric EQ

　　Automatic Level Control (ALC)

　　Excursion Limiter

　　Speaker Power Limiter

　　Speaker Distortion Limiter

　　Microphone Automatic Gain Control and Noise Gate

　　Dual I2S/PCM/TDM Digital Audio Interfaces

　　Asynchronous Digital Mixing

　　Supports Master Clock Frequencies from 10MHz to 60MHz

　　RF Immune Analog Inputs and Outputs

　　Extensive Click-and-Pop Reduction Circuitry

　　I2C Control Interface

　　63 WLP Package (3.80mm x 3.30mm, 0.4mm Pitch)

　　图1。MAX9888简化方框图

　　图2。MAX9888功能方框图

　　图3。MAX9888麦克风输入方框图

　　图4。MAX9888线输入方框图

　　图5。MAX9888 ADC输入混合器方框图

　　图6。MAX9888 录音通路信号处理方框图

　　图7。MAX9888 数字信号路由框图

　　图8。MAX9888 数字带通滤波方框图

　　图9。MAX9888 扬声器放大器通路方框图

　　图10。MAX9888 扬声器放大器信号处理方框图

　　图11。MAX9888 耳机放大器方框图

　　图12。MAX9888 输出旁路开关方框图

　　图13。MAX9888采用模拟麦克风输入和旁路开关的典型应用电路图

　　图14。MAX9888采用数字麦克风输入和接收放大器的典型应用电路图