原标题：Silabs Si270x降EMI音频D类放大解决方案

　　Silabs公司的Si2704/05/06/07是降EMI的数字音频处理D类放大器, 集成了功率级,PWM DAC和数字音频处理(DAP),以简化低成本高效率系统的设计. Si270x具有数字输入Delta-Sigma PWM,正在申请专利的降EMI,AM波段无噪音陷波滤波器,能向3欧姆BTL输出2x5W功率,PSRR大于50dB时的效率88%,THD优于 0.1%时的动态范围为95dB,主要应用在PMP/MP3坞站,手持消费类电子,有源/无线扬声器,TV和监视器以及TV声卡等.本文介绍了Si2704/05/06/07主要特性, 功能方框图, 典型应用电路图和材料清单,以及多种系统配置图与Si270x-EVB D类放大器开发套件主要特性.

　　The Si2704/05/06/07 EMI mitigating 2.1 digital audio processing Class D amplifier integrates a power stage, PWM DAC, and digital audio processing (DAP) for simplified, low cost, power efficient system designs in consumer audio electronics. The digital input amplifier features delta-sigma PWM and innovative EMI mitigation technology for producing high-quality audio while effectively managing PWM switching noise for enhanced EMI compliance and AM/FM radio co-existence, while also being GSM/iPhone friendly.

　　Si2704/05/06/07主要特性:

　　Digital input Delta-Sigma PWM

　　Patent-pending EMI mitigation

　　AM radio band noise-free notch

　　GSM/iPhone friendly

　　Wideband PWM carrier spreading

　　Power stage slew rate control

　　Power stage feedback for PSR/THD

　　2x 5 W @ 3 ohm BTL; 2x 3 W @ 8 ohm BTL

　　88% efficiency with >50 dB PSRR

　　95 dB dynamic range and <0.1% THD

　　Stereo PWM DAC line analog outputs

　　Master/slave I2S w/ 3 inputs & 1 output

　　Automatic digital audio rate detection

　　Standard audio rates from 32–192 kHz

　　Audio activity detector w/ auto-standby

　　Operates from external XTAL or clock

　　Buffered master/regulator clock output

　　Programmable 7 band parametric EQ, dynamic range compressor, tone control

　　Crossbar input mixer with scaling

　　Digital tone and alert generation

　　128 dB volume control in 0.5 dB steps

　　Multiple low power operating modes

　　Over-current and over-temperature detection w/ auto recovery

　　Pop and click free operation

　　Standard 2-wire control w/ 2 addresses

　　System flexibility w/ 3 multi-function pins

　　Dual supply voltage: 2.7–3.6 V main and 4.0–6.6 V power stage

　　Available in 4x4 24-pin Power QFN and 7x7 48-pin Power eTQFP package

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　　Both Pb-free/RoHS compliant

　　Si2704/05/06/07应用:

　　PMP/MP3 docking stations

　　Portable consumer audio electronics

　　Table top and portable radios

　　Active/wireless speakers

　　TVs and monitors

　　TV sound bars

　　图1.Si2704/05/06/07功能方框图

　　图2.Si2704/05/06/07典型应用电路图

　　典型应用电路材料清单(BOM):

　　图3.Si270x PMP坞站系统基本配置图

　　图4.Si270x 带无线电和数字媒体控制的PMP坞站系统配置图

　　图5.Si270x立体声双向扬声器系统配置图

　　图6.Si270x TV声卡系统配置图

　　Si270x-EVB D类放大器开发套件

　　Si270x-EVB Class D Amplifier Development Kit

　　图7.Si270x-EVB D类放大器开发套件外形图

　　The Si270x Class D amplifier EVB consists of a baseboard and a daughter card. The baseboard is common and shared among all the Si270x 5 W per channel Class D audio amplifier daughter cards. The Si270x-EVB kit addresses the entire Si270x family of Class D amplifier products.

　　The daughter card is populated with the Si2707 Class D amplifier which provides the following:

　　EMI mitigation

　　Volume and tone controls

　　EQ and Dynamic Range Compressor DSP functions

　　Tunable noise-free notch for AM radio coexistence

　　The Si270x Class D amplifier EVB is supported by a full function graphical user interface (GUI) that runs on a standard PC and is connected to the EVB via USB. The baseboard includes the Si4730 AM/FM tuner, a stereo analog input, as well as an optical SPDIF input for digital audio sources. The daughter card also includes the required output filtering network. Speakers with impedances of 4 Ω and larger may be directly driven from this board; a separate line level output is provided.

　　The Si270x-EVB Class D Amplifier development kit includes:

　　Si270x Evaluation Board

　　External power supply

　　AM/FM adapter card and antennas cable

　　Audio cable

　　Documentation and software CD