NXP 公司的TFA9879是高效无滤波器单声道D类音频放大器,具有两个独立使用的数字输入,它包括了两个支持各种声音处理特性的处理器,如5波段参量均衡器,单独的低音和高音控制(−18 dB到+18 dB),动态范围压缩器,软件剪辑控制和音量控制(−70 dB 到+24 dB), 工作电压2.5 V 到5.5 V,主要用在手机,PND,笔记本电脑,手提游戏机和MP3/MP4播放器.本文介绍了TFA9879主要特性, 方框图, 可供选择的输出低通LC滤波器以及典型应用电路图.

The TFA9879 is a high-efficiency filter-free mono class-D audio amplifier with two separate digital inputs for mobile applications.
The TFA9879 contains a processor that supports a range of sound processing features including a 5-band parametric equalizer, separate bass and treble control, a dynamic range compressor, soft clip control and volume control. Excellent audio performance combined with high Power Supply Rejection Ratio (PSRR) is achieved through the use of a closed loop configuration.
Two independent digital audio inputs (I2S-bus / PCM / IOM2) are available for connecting both a baseband and a multimedia processor.
The TFA9879 is available in a HVQFN24 package.
TFA9879主要特性:
通用特性:
Closed loop amplifier for:
High power supply rejection ratio
Excellent audio performance
Digital input for high RF immunity
High efficiency for maximizing battery life
Wide supply voltage range (fully operational from 2.5 V to 5.5 V)
Delivers high output power into 4 Ω and 8 Ω load impedances
Phase-Locked Loop (PLL); no system clock required
Protection including diagnostics via I2C-bus:
OverCurrent Protection (OCP) to protect against short circuits across the speaker,to the supply line or to ground
OverTemperature Protection (OTP)
Digital inputs protected with UnderFrequency Protection (UFP), OverFrequency Protection (OFP) and Invalid Bit-clock Protection (IBP)
‘Pop noise’ free at power-up/power down, during sample rate switching and when switching between digital inputs
Four separate I2C-bus addresses for multi-channel applications
1.8 V / 3.3 V tolerant digital inputs
Only three external components required
可编程DSP:
Digital volume control (−70 dB to +24 dB)
Digital parametric 5-band equalizer
Bass and treble control (−18 dB to +18 dB)
Dynamic range compressor:
Programmable attack and release levels
Programmable attack and release rates
Soft and hard mute control
Programmable DC blocking via high-pass filter
Power limiter (0 dB to −124 dB in 0.5 dB steps)
Zero crossing volume control
Stereo-to-mono down-mix function
支持输字音频输入的接口格式:
I2S formats (fs = 8 kHz to 96 kHz):
Philips standard I2S-bus
Japanese I2S-bus MSB-justified
Sony I2S-bus LSB-justified
PCM / IOM2 formats (fs = 8 kHz or fs = 16 kHz):
Long frame sync
Short frame sync
TFA9879应用:
Mobile phones
Portable Navigation Devices (PND)
PDAs
Notebooks
Portable gaming devices
MP3 and MP4 players

图1.TFA9879方框图

图2.TFA9879可选择低通LC滤波器

图3.简化的TFA9879应用框图