原标题：Maxim MAX98357A PCM输入D类音频放大器解决方案

　　Maxim公司的MAX98357A/MAX98357B是数字脉码调制(PCM)输入D类放大器,提供AB类音频性能和D类效率,有五个可选择的增益设定(3dB, 6dB, 9dB, 12dB和15dB),单电源2.5V-5.5V工作,5V 4Ω时的输出功率为3.2W,效率92% (RL = 8Ω, POUT = 1W),输出噪音25μVRMS (AV = 15dB),1kHz时的THD+N为0.015%,主要用在笔记本电脑和上网本(Netbook),手机和平板电脑.本文介绍了MAX98357A/MAX98357B主要特性,功能框图和几种应用电路,以及MAX98357开发板DEV(WLP)主要特性,框图,电路图,材料清单和PCB设计图.

　　The MAX98357A/MAX98357B are digital pulse-code mod­ulation (PCM) input Class D power amplifiers that provide Class AB audio performance with Class D efficiency. These ICs offer five selectable gain settings (3dB, 6dB, 9dB, 12dB, and 15dB) in I2S/left-justified mode set by a single gain select input and a fixed 12dB gain in TDM mode.

　　The digital audio interface is highly flexible with the MAX98357A supporting I2S data and the MAX98357B supporting left-justified data. Both ICs support 8 channel time division multiplexed (TDM) data. The digital audio interface accepts specified sample rates between 8kHz and 96kHz for all supported data formats. The ICs can be configured to produce a left channel, right channel, or (left/2 + right/2) output from the stereo input data. The ICs operate using 16/24/32-bit data for I2S and left-justified modes as well as 16-bit or 32-bit data using TDM mode. The ICs eliminate the need for the external MCLK signal that is typically used for PCM communication. This reduc­es EMI and possible board coupling issues in addition to reducing the size and pin count of the ICs.

　　The ICs also feature a very high wideband jitter toler­ance (12ns typ) on BCLK and LRCLK to provide robust operation.Active emissions-limiting, edge-rate limiting, and over­shoot control circuitry greatly reduce EMI. A filterless spread-spectrum modulation scheme eliminates the need for output filtering found in traditional Class D devices and reduces the component count of the solution.

　　The ICs are available in 9-pin WLP (1.345mm x 1.435mm x 0.64mm) and 16-pin TQFN (3mm x 3mm x 0.75mm) packages and are specified over the -40 ℃ to +85℃ tem­perature range.

　　MAX98357A/MAX98357B主要特性:

　　Single-Supply Operation (2.5V to 5.5V)

　　3.2W Output Power into 4Ω at 5V

　　2.4mA Quiescent Current

　　92% Efficiency (RL = 8Ω, POUT = 1W)

　　25μVRMS Output Noise (AV = 15dB)

　　Low 0.015% THD+N at 1kHz

　　No MCLK Required

　　Sample Rates of 8kHz to 96kHz

　　Supports Left, Right, or (Left/2 + Right/2) Output

　　Sophisticated Edge Rate Control Enables Filterless Class D Outputs

　　77dB PSRR at 1kHz

　　Low RF Susceptibility Rejects TDMA Noise from GSM Radios

　　Extensive Click-and-Pop Reduction Circuitry

　　Robust Short-Circuit and Thermal Protection

　　Available in Space-Saving Packages: 1.345mm x 1.435mm WLP (0.4mm Pitch) and 3mm x 3mm TQFN

　　MAX98357A/MAX98357B应用:

　　Notebook and Netbook Computers

　　Cellular Phones

　　Tablets

　　图1.MAX98357A/MAX98357B功能框图

　　图2.MAX98357A/MAX98357B增益6dB左路PCM工作电路

　　图3.MAX98357A/MAX98357B增益12dB左路PCM工作电路

　　图4.MAX98357A/MAX98357B增益6dB右路PCM工作电路

　　图5.MAX98357A/MAX98357B增益6dB(左路/2+右路/2)PCM工作电路

　　图6.MAX98357A/MAX98357B采用两个IC的立体声PCM工作电路

　　图7.MAX98357A/MAX98357B增益12dB通路TDM工作电路

　　MAX98357开发板DEV(WLP)

　　The MAX98357 development board (DEV board) is a fullyassembled and tested PCB that evaluates the MAX98357I2S digital input Class D power amplifier. The DEV boardoperates from a single 2.5V to 5.5V DC power supply andis capable of delivering 3.2W into a 4Ω load. The deviceoutputs can be connected directly to a speaker load forfilterless applications. However, a filter can be added toease evaluation. The MAX98357A accepts standard I2Sdata and the MAX98357B accepts left-justified digital audio data. Both versions also support 8-channel TDMaudio data.

　　The MAX98357 evaluation system (EV system) includesthe MAX98357 DEV board and Maxim Integrated’s audiointerface board (AUDINT001 board).

　　The AUDINT001 board provides an easy-to-use USBaudio-to-I2S converter. This allows for any computer tobecome a digital audio source, which can be used toevaluate the devices. The AUDINT001 board can also beused to power the MAX98357. This allows for a completeevaluation from a single USB connection.

　　MAX98357开发板DEV(WLP)主要特性:

　　●● 2.5V to 5.5V Single-Supply Operation

　　●● Only a Single External Component (VDD Capacitor)Required in Many Applications

　　●● I2S, Left-Justified, or TDM Input

　　●● Five Selectable Gains (3db, 6dB, 9dB, 12dB, and15dB)

　　●● Audio Channel Select (Left, Right, and Mono Mix)

　　●● Filterless Operation

　　●● Optional Class D Output Filters for Ease ofEvaluation

　　●● Proven PCB Layout

　　●● Fully Assembled and Tested

　　MAX98357开发板DEV(WLP)材料清单:

　　详情请见:

MAX98357DEV_WLP-MAX98357EVSYS_WLP.pdf

MAX98357A-MAX98357B.pdf