Wolfson公司的WM8994是高度集成智能手机用超低功耗高保真音频CODEC,具有高保真24位4路DAC和2路ADC,立体声DAC播放的SNR为100dB(A加权),1W立体声/2W单声道D类/AB类扬声器驱动器,无电容W类耳机驱动器,智能的MIC接口和高性能模拟MIC接口,主要应用在智能手机和音乐手机,手提导航仪和移动互联网设备(MID).本文介绍了WM8994主要特性,方框图, 采用数字MIC和数字音频接口的智能手机方框图以及WM8994评估板,功能方框图,详细电路图和所用材料清单(BOM).

The WM8994 is a highly integrated ultra-low power hi-fi CODEC designed for smartphones and other portable devices rich in multimedia features.

An integrated stereo class D/AB speaker driver and class W headphone driver minimize power consumption during audio playback.

The device requires only Vbatt and a 1.8V supply, generating all other internal supply rails from integrated LDOs.

Stereo full duplex asynchronous sample rate conversion and multi-channel digital mixing combined with powerful analogue mixing allow the device to support a huge range of different architectures and use cases.

A fully programmable parametric EQ provides speaker compensation and a dynamic range controller can be used in the ADC or DAC paths for maintaining a constant signal level, maximizing loudness and protecting speakers against overloading and clipping.

A smart digital microphone interface provides power regulation, a low jitter clock output and decimation filters for up to four digital microphones. A MIC activity detect with interrupt is available.

Active ground loop noise rejection and DC offset correction help prevent pop noise and suppress ground noise on the headphone outputs.

WM8994主要特性:

• Hi-Fi 24-bit 4-channel DAC and 2-channel ADC

• 100dB SNR during stereo DAC playback (‘A’ weighted)

• Smart MIC interface

- Power, clocking and data input for up to four digital MICs

- High performance analogue MIC interface

- MIC activity monitor & interrupt allows processor to sleep

• 1W stereo / 2W mono class D/AB speaker driver

• Capless class W headphone drivers

- Integrated charge pump

- 6mW total power for DAC playback to headphones

• 4 line outputs (single-ended or differential)

• BTL earpiece driver

• Digital audio interfaces for multi-processor architecture

- Asynchronous stereo duplex sample rate conversion

- Powerful mixing and digital loopback functions

• ReTuneTM Mobile 5-band, 6-channel parametric EQ

• Programmable dynamic range controller

• Dual FLL provides all necessary clocks

- Self-clocking modes allows processor to sleep

- All standard sample rates from 8kHz to 96kHz

• Active noise reduction circuits

- DC offset correction removes pops and clicks

- Ground loop noise cancellation

• Integrated LDO regulators

• 72-ball W-CSP package (4.511mm x 4.023mm x 0.7mm)

WM8994应用:

• Smartphones and music phones

• Portable navigation

• Mobile internet devices