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Wolfson WM8961超低功耗立体声CODEC方案

作者:  时间:2009-06-25 10:47  来源:eaw
Wolfson 公司的WM8961是超低功耗立体声CODEC,集成了1W立体声D类扬声器驱动器和参考地耳机驱动器,非常适合手提音频设备如游戏机, DVD播放器和移动多媒体应用. WM8961的DAC在48kHz和1.8V时的SNR(A权重)为98dB,THD为-83dB, WM8961的ADC在48kHz和1.8V时的SNR(A权重)为88dB,THD为-75dB;立体声D类扬声器驱动器,每路能向8欧姆BTL扬声器输出1W,每路耳机在-80dB时能输出高达22mW.模拟电源1.71V到2.0V,电荷泵1.71V到2.0V,数字电源1.62V到2.0V,MIC偏压放大器电源1.71V到3.6V.本文介绍了WM8961主要特性,方框图, 推荐的耳机输出配置和WM8961外接元件,以及WM8961评估板的详细电路图和所用材料清单(BOM).

WM8961: Ultra-Low Power Stereo CODEC with 1W Stereo Class D Speaker Drivers and Ground Referenced Headphone Drivers

The WM8961 is a low power, high quality stereo CODEC designed for portable digital audio applications.

An integrated charge pump provides a ground referenced output which removes the need for DC-blocking capacitors on the output, and uses the Wolfson ‘Class-W’ amplifier techniques - incorporating an innovative dual-mode charge pump architecture - to optimise efficiency and power consumption during playback.

A DC Servo is used to reduce DC ground offsets. This improves power consumption and minimises pops and clicks. Stereo class D speaker drivers provide 1W per channel into 8ohm loads with a 5V supply. Low leakage, excellent PSRR and pop/click suppression mechanisms also allow direct battery connection to the speaker supply. Flexible speaker boost settings allow speaker output power to be maximised while minimising other analogue supply currents.

Control sequences for audio path setup can be pre-loaded and executed by an integrated sequencer to reduce software driver development and eliminate pops and clicks via Wolfson’s SilentSwitch technology.

Flexible input configuration: a stereo input or two mono inputs on Lch or Rch ADC, with a complete microphone interface. External component requirements are drastically reduced as no separate microphone, speaker or headphone amplifiers are required. Advanced on-chip digital signal processing performs automatic level control for the microphone or line input.

Stereo 24-bit sigma-delta ADCs and DACs are used with low power over-sampling digital interpolation and decimation filters and a flexible digital audio interface.

The WM8961 operates at analogue supply voltages down to 1.71V, although the digital supplies can operate at voltages down to 1.62V to save power. The speaker supply can operate at up to 5.5V, providing 1W per channel into 8 loads. Unused functions can be disabled using software control to save power.

The WM8961 is supplied in a very small and thin 5x5mm QFN package, ideal for use in hand-held and portable systems.

WM8961主要特性:

DAC SNR 98dB (‘A’weighted), THD -83dB at 48kHz, 1.8V

ADC SNR 88dB (‘A’weighted), THD -75dB at 48kHz, 1.8V

Stereo Class D Speaker Driver

1W per channel into 8ohm BTL speakers.

Flexible internal switching clock

Wolfson ‘Class-W’ultra-low power headphone Driver

Up to 22mW per channel output power at -80dB

THD+N into 16 ohm at 1.8V

Ground Referenced

Low offset (+/- 1.5mV)

Pop and click suppression

Control sequencer for pop-minimised start-up and shut-down

Single register write for default start-up sequence

Microphone Interface

Single ended stereo input

Integrated low noise MICBIAS

Programmable ALC / Limiter and Noise Gate

Low Power Consumption

6.99mW headphone playback (1.8V supplies, Low Power mode)

Low Supply Voltages

Analogue 1.71V to 2.0V (Speaker supply up to 5.5V)

Charge pump 1.71V to 2.0V

MIC bias amp supply 1.71V to 3.6V

Digital 1.62V to 2.0V

2-wire serial control interface including read-back

Sample rates: 8, 11.025, 12, 16, 22.05, 24, 32, 44.1, 48

5x5x0.9mm 32 pin QFN package

WM8961应用:

Games consoles

Portable media / DVD players

Mobile multimedia



图1.WM8961方框图



图2.推荐的耳机输出配置



图3.推荐的WM8961外接元件

WM8961评估板

The WM8961 is a high performance ultra-low power stereo CODEC optimised for portable audio applications.

This evaluation platform has been designed to allow the user ease of use and give optimum performance in device measurement. The evaluation platform and documentation should be used in conjunction with the latest version of the WM8961 datasheet, which gives device functionality information as well as performance figures and typical applications.

The evaluation platform includes a USB interface for configuring WM8961 register settings, and a SPDIF interface to allow audio streaming to and from the evaluation platform.



图4. WM8961评估板方框图



图5. WM8961评估板S/PDIF输入电路图



图6. WM8961评估板USB I/F电路图



图7. WM8961评估板音频I/F电平转移电路图



图8. WM8961评估板控制I/F电平转移电路图



图9. WM8961评估板器件位置图



图10. WM8961评估板无源模拟输入电路图



图11. WM8961评估板无源模拟输出电路图



图12. WM8961评估板D类扬声器输出电路图



图13. WM8961评估板USB电源电路图



图14. WM8961评估板外接电源电路图



图15. WM8961评估板ID



图16. WM8961评估板参考表

材料清单(BOM):







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