TI(NS) LM48901四路音频D类功率放大方案

TI(NS) 公司的LM48901是四路音频D类功率放大器,输出级采用前沿速率恐怖行动(ERC)PWM架构,能降低RF辐射而维持音频质量和效率,它的I2S接口和标准串行音频接口兼容,差分输入立体声ADC,平行输出模式,RL = 8Ω, THD+N ≤10%时的输出功率为1.7W ,RL = 4Ω, THD+N ≤10%时为2.8W (typ),而典型的THD+N为0.06%,主要用在便携式计算机,平板电脑,台式电脑,条形音箱,多媒体设备,MP3播放器附件和坞站.本文介绍了LM48901主要特性和指标,音频放大器应用电路,通路音频放大器应用电路和I2C_EN/I2C_EX菊花链案例应用电路以及评估板主要特性.

The LM48901 is a quad Class D amplifier that utilizes National’s proprietary spatial sound processor to create an enhanced sound stage for portable multimedia devices. The Class D output stages feature National’s edge rate control (ERC) PWM architecture that significantly reduces RF emissions while preserving audio quality and efficiency.

The LM48901’s flexible I 2S interface is compatible with standard serial audio interfaces. A stereo differential-input ADC gives the device the ability to process analog stereo audio signals.

The LM48901 is configured through an I 2C compatible interface and is capable of delivering 2.8W/channel of continuous output power into an 4Ω load with less than 10% THD+N. A 2.1 mode pairs two output drivers in parallel, increasing current drive for 4Ω loads.

Output short circuit and thermal overload protection prevent the device from being damaged during fault conditions. Superior click and pop suppression eliminates audible transients on power-up/down and during shutdown. The LM48901 is available in space saving microSMD and LLP packages.

LM48901 主要特性:

Spatial Sound Processing

I 2S Compatible Input

Differential-Input Stereo ADC

Edge Rate Control Reduces EMI while Preserving Audio Quality and Efficiency

Paralleled Output Mode

Short Circuit and Thermal Overload Protection

Minimum external components

Click and Pop suppression

Micro-power shutdown

Available in space-saving micro SMD and LLP packages

LM48901 应用:

Laptops

Tablets

Desktop Computers

Sound Bars

Multimedia Devices

MP3 Player Accessories

Docking Stations

LM48901 主要指标:
■ SNR (A-Weighted)
87dBA (typ)
■ Output Power/channel, PVDD = 5V

  RL = 8Ω, THD+N ≤10%
1.7W (typ)
  RL = 4Ω, THD+N ≤10%
2.8W (typ)
■ THD+N
0.06% (typ)
■ Efficiency/Channel
89% (typ)
■ pSRR at 217Hz
71dB (typ)
■ Shutdown current
1μA (typ)

图1.LM48901典型音频放大器应用电路

图2.LM48901通路音频放大器应用电路

图3.LM48901 I2C_EN/I2C_EX菊花链案例应用电路

The LM49801 evaluation board accepts three audio input formats: stereo differential analog, SPDIF, or I2S. Multiple boards are easily cascaded, increasing the number of channels. The LM48901 can also be configured as a 2.1 amplifier for stereo + subwoofer applications.

The board is controlled though a Windows- and Mac OSX-compatible graphic user interface (GUI). The GUI configures the device, loads spatial coefficients, and provides a graphic equalizer. The board connects to a computer through a USB interface device (included).

System Components

Evaluation system hardware

LM49801SQ Evaluation Board

USB to I2C Interface

图4.LM49801评估板外形图
详情请见:
51007