Wolfson WM8918高性能超低功耗立体声DAC方案

Wolfson 公司的WM8918是用于手提音频设备的高性能超低功耗立体声DAC，DAC到耳机播放的静态功耗3.8mW，DAC的SNR为96dB，THD为-86dB，标准取样速率从8kHz到96kHz，集成的PLL提供了所有必须的时钟，主要用在PMP，无线手机和游戏机等。本文介绍了WM8918主要特性，音频信号通路框图，推荐的外接元件图以及WM8918-6201-FL32-M-REV1用户Mini板配置图，多种应用的信号通路图，电路图和材料清单，PCB布局图。
The WM8918 is a high performance ultra-low power stereo DAC optimised for portable audio applications.
The device features stereo ground-referenced headphone amplifiers using the Wolfson ‘Class-W’ amplifier techniques - incorporating an innovative dual-mode charge pump architecture - to optimise efficiency and power consumption during playback. The ground-referenced headphone and line outputs eliminate AC coupling capacitors, and both outputs include common mode feedback paths to reject ground noise.
Control sequences for audio path setup can be pre-loaded and executed by an integrated control write sequencer to reduce software driver development and minimise pops and clicks via Wolfson’s SilentSwitch™ technology.
The analogue input stage can be configured for single ended or differential inputs. Up to 3 stereo microphone or line inputs may be connected. The input impedance is constant with PGA gain setting.
A stereo digital microphone interface is provided, with a choice of two inputs. The analogue or digital microphone inputs can be mixed into the headphone or line output paths.
A dynamic range controller provides compression and level control to support a wide range of portable recording applications in conjunction with the digital microphone interface. Anti-clip and quick release features offer good performance in the presence of loud impulsive noises.
ReTuneTM Mobile 5-band parametric equaliser with fully programmable coefficients is integrated for optimization of speaker characteristics. Programmable dynamic range control is also available for maximizing loudness,...