欢迎访问ic37.com |
会员登录 免费注册
发布采购

WM8940GEFL/RV 参数 Datasheet PDF下载

WM8940GEFL/RV图片预览
型号: WM8940GEFL/RV
PDF下载: 下载PDF文件 查看货源
内容描述: 单声道编解码器与扬声器驱动器 [Mono CODEC with Speaker Driver]
分类和应用: 解码器驱动器编解码器
文件页数/大小: 85 页 / 819 K
品牌: WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
 浏览型号WM8940GEFL/RV的Datasheet PDF文件第12页浏览型号WM8940GEFL/RV的Datasheet PDF文件第13页浏览型号WM8940GEFL/RV的Datasheet PDF文件第14页浏览型号WM8940GEFL/RV的Datasheet PDF文件第15页浏览型号WM8940GEFL/RV的Datasheet PDF文件第17页浏览型号WM8940GEFL/RV的Datasheet PDF文件第18页浏览型号WM8940GEFL/RV的Datasheet PDF文件第19页浏览型号WM8940GEFL/RV的Datasheet PDF文件第20页  
WM8940  
Pre-Production  
DEVICE DESCRIPTION  
INTRODUCTION  
The WM8940 is a low power audio codec combining a high quality mono audio DAC and ADC, with  
flexible line and microphone input and output processing. Applications for this device include digital  
still cameras or camcorders with mono audio, record and playback capability.  
FEATURES  
The chip offers great flexibility in use, and so can support many different modes of operation as  
follows:  
MICROPHONE INPUTS  
Two microphone inputs are provided, allowing for either a differential microphone input or a single  
ended microphone to be connected. These inputs have a user programmable gain range of -12dB  
to +35.25dB using internal resistors. After the input PGA stage comes a boost stage which can add  
a further 20dB of gain. A microphone bias is output from the chip which can be used to bias the  
microphones. The signal routing can be configured to allow manual adjustment of mic levels, or to  
allow the ALC loop to control the level of mic signal that is transmitted.  
Total gain through the microphone paths of up to +55.25dB can be selected.  
PGA AND ALC OPERATION  
A programmable gain amplifier is provided in the input path to the ADC. This may be used manually  
or in conjunction with a mixed analogue/digital automatic level control (ALC) which keeps the  
recording volume constant.  
AUX INPUT  
The device includes a mono input, AUX, that can be used as an input for warning tones (beep) etc.  
The output from this circuit can be summed into the mono output and/or the speaker output paths,  
so allowing for mixing of audio with ‘backing music’ etc as required. This path can also be summed  
into the input in a flexible fashion, either to the input PGA as a second microphone input or as a line  
input. The configuration of this circuit, with integrated on-chip resistors allows several analogue  
signals to be summed into the single AUX input if required.  
ADC  
The mono ADC uses a multi-bit high-order over sampling architecture to deliver optimum  
performance with low power consumption. Various sample rates are supported, from the 8ks/s rate  
typically used in voice dictation, up to the 48ks/s rate used in high quality audio applications.  
HI-FI DAC  
The hi-fi DAC provides high quality audio playback suitable for all portable mono audio type  
applications.  
DIGITAL FILTERING  
Advanced Sigma Delta Converters are used along with digital decimation and interpolation filters to  
give high quality audio at sample rates from 8ks/s to 48ks/s.  
Application specific digital filters are also available which help to reduce the effect of specific noise  
sources such as wind noise or narrowband noise from other parts of the system. The filters include a  
programmable ADC high pass filter and four fully programmable ADC notch filters.  
OUTPUT MIXING AND VOLUME ADJUST  
Flexible mixing is provided on the outputs of the device; a mixer is provided for the speaker outputs,  
and an additional mono summer for the mono output. These mixers allow the output of the DAC, the  
output of the ADC volume control and the Auxiliary input to be combined. The output volume can be  
adjusted using the integrated digital volume control and there is additional analogue gain adjustment  
capability on the speaker output.  
AUDIO INTERFACES  
The WM8940 has a standard audio interface, to support the transmission of audio data to and from  
the chip. This interface is a 4 wire standard audio interface which supports a number of audio data  
formats including I2S, DSP Mode, MSB-First, left justified and MSB-First, right justified, and can  
operate in master or slave modes.  
Pre-Production, Rev 3.0, February 2007  
16  
w
 复制成功!