原创 Wolfson WM8742 24位音频立体声DAC方案

 2009-9-23 08:26  3452 3 3 分类: MCU/ 嵌入式


作者：时间：2009-05-06 来源:

Wolfson公司的WM8742是非常高性能的24位音频立体声DAC,设计用于专业录音系统,A/V接收器和高档CD,DVD和家庭影院. WM8742支持PCM数据输入,字长度从16位到32位,取样速率高达192kHz,同时还支持DSD比特流数据格式,包括直接的DSD和从PCM转换来的DSD格式. WM8742的功能还包括精细的音量控制和软静音控制,数字去加重以及各种高档数字滤波器响应,随后是数字内插滤波器,多比特sigma delta调制器和立体声DAC.本文介绍了WM8742的`主要特性,方框图, 外接元件连接图和外接滤波器电路图. WM8742: 24-bit 192kHz DAC with Advanced Digital Filtering The WM8742 is a very high performance stereo DAC designed for audio applications such as professional recording systems, A/V receivers and high specification CD, DVD and home theatre systems. The device supports PCM data input word lengths from 16 to 32-bits and sampling rates up to 192kHz. The WM8742 also supports DSD bitstream data format, in both direct DSD and PCM-converted DSD modes. The WM8742 includes fine resolution volume and soft mute control, digital de-emphasis and a range of advanced digital filter responses, followed by a digital interpolation filter, multi-bit sigma delta modulator and stereo DAC. Wolfson’s patented architecture optimises the linearity of the DAC and provides maximum insensitivity to clock jitter. The digital filters include several selectable roll-off and performance characteristics. The user can select between standard sharp or slow roll-off responses. In addition, the WM8742 includes a selection of advanced digital filter characteristics including non-half band filters and minimum phase filters. This flexibility provides a range of benefits, such as significantly reduced pre-ringing and minimal group delay. The internal digital filters can also be by-passed and the WM8742 used with an external digital filter. The WM8742 supports two connection schemes for audio DAC control. The 2/3 wire serial control interface provides access to all features. A range of features can also be accessed by hardware control interface. The WM8742 is available in a convenient 28-SSOP package, and is pin compatible with the WM8740 and WM8741. WM8742主要特性: Advanced Ultra High Performance Multi-bit Sigma-Delta Architecture 126dB SNR (‘A’-weighted mono @ 48kHz) 123dB SNR (‘A’-weighted stereo @ 48kHz) 121dB SNR (non-weighted stereo @ 48kHz) 100dB THD @ 48kHz Differential analogue voltage outputs High tolerance to clock jitter PCM Mode Sampling frequency: 32kHz to 192kHz Input data word length support: 16 to 32-bit Supports all standard audio interface formats Selectable advanced digital filter responses Includes linear/minimum phase and range of tailored characteristics Enables low pre-ringing, minimal latency Optional interface to industry standard external filters Digital volume control in 0.125dB steps with soft ramp and soft mute Anti-clipping mode to prevent distortion even with input signals recorded up to 0dB Selectable de-emphasis support Zero Flag output DSD Mode DSD bit-stream support for SACD applications Support for normal or phase modulated bit-streams Direct or PCM converted DSD paths (DSD Plus) DSD mute Hardware or software control modes: 2 and 3 wire serial control interface support Pin compatible with WM8740 and WM8741 4.5V to 5.5V analogue, 3.0V to 3.6V digital supply operation 28-lead SSOP Package 应用: Professional audio systems CD, DVD, SACD audio Home theatre systems A/V receivers 图1.WM8742方框图图2.WM8742外接元件连接图图3. WM8742外接滤波器电路图