Maxim 公司的MAX9888是采用FlexSound技术的全特性立体声音频CODEC,立体声DAC的DR为100dB(8kHz fS 96kHz),立体声ADC的DR为91dB(8kHz fS 96kHz),立体声低EMI D类放大器950mW/每路,集成了DirectDrive耳机放大器和差分接收放大器,其高性能和低功耗适合用在手持设备.本文介绍了MAX9888主要特性,功能方框图,典型应用电路图以及MAX9888评估板主要特性,方框图,电路图和材料清单. 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 opera-tion 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 loud-speaker performance by optimizing the signal level and frequency response while limiting the maximum distor-tion 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功能框图

图2.MAX9888典型应用电路图:采用模拟麦克风输入和旁路开关

图3.MAX9888典型应用电路图:采用数字麦克风输入和接收放大器

MAX9888评估板
The MAX9888 evaluation kit (EV kit) is a fully assembled and tested circuit board that evaluates the MAX9888 audio codec. The MAX9888 is an integrated audio codec including microphone amplifiers, line amplifiers, an earpiece amplifier, stereo Class D amplifiers, stereo DirectDriveM headphone amplifiers, and digital signal processing. The EV kit also includes Windows XPM-,Windows VistaM-, and WindowsM 7-compatible software that provides a simple graphical user interface (GUI) for exercising the features of the device.
The EV kit provides access to all analog and digital inputs/outputs on the device. To enable easy connection to a wide range of audio sources, audio devices are included to convert both USB data and S/PDIF data to I2S.
The EV kit integrates a MAXQ2000 microcontroller to enable I2C communication with devices on the EV kit.
The EV kit software, running on a Windows PC, communicates with the EV kit over a standard USB port. The EV kit software provides an intuitive interface to exercise the
functions of the device.
The EV kit comes with a MAX9888EWY+ installed.

MAX9888评估板主要特性:
2.8V to 5.5V Single-Supply Operation
Proven Audio PCB Layout
On-Board USB-to-I2C Interface
On-Board USB-to-I2S Converter
On-Board S/PDIF Transceiver
On-Board Clock Source
On-Board Digital Microphone
Evaluates the MAX9888EWY+ in a 3.8mm x
3.3mm, 63-Bump WLP Package
Windows XP-, Windows Vista-, and Windows
7-Compatible Software
Fully Assembled and Tested

图4.MAX9888评估板方框图

图5.MAX9888评估板电路图(1)

图6.MAX9888评估板电路图(2)

图7.MAX9888评估板电路图(3)

图8.MAX9888评估板电路图(4)

图9.MAX9888评估板电路图(5)

MAX9888评估板材料清单(BOM):





图10.MAX9888评估板元件布局图