NXP 公司的TFA9879是高效無(wú)濾波器單聲道D類(lèi)音頻放大器,具有兩個(gè)獨立使用的數字輸入,它包括了兩個(gè)支持各種聲音處理特性的處理器,如5波段參量均衡器,單獨的低音和高音控制(−18 dB到+18 dB),動(dòng)態(tài)范圍壓縮器,軟件剪輯控制和音量控制(−70 dB 到+24 dB), 工作電壓2.5 V 到5.5 V,主要用在手機,PND,筆記本電腦,手提游戲機和MP3/MP4播放器.本文介紹了TFA9879主要特性, 方框圖, 可供選擇的輸出低通LC濾波器以及典型應用電路圖.

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
可編程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
支持輸字音頻輸入的接口格式:
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應用:
Mobile phones
Portable Navigation Devices (PND)
PDAs
Notebooks
Portable gaming devices
MP3 and MP4 players

圖1.TFA9879方框圖

圖2.TFA9879可選擇低通LC濾波器

圖3.簡(jiǎn)化的TFA9879應用框圖