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WM8976GEFL/RV 参数 Datasheet PDF下载

WM8976GEFL/RV图片预览
型号: WM8976GEFL/RV
PDF下载: 下载PDF文件 查看货源
内容描述: 立体声编解码器,扬声器驱动器 [Stereo CODEC With Speaker Driver]
分类和应用: 解码器驱动器编解码器电信集成电路PC
文件页数/大小: 108 页 / 1227 K
品牌: WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
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WM8976  
Pre-Production  
NOTCH FILTER WORKED EXAMPLE  
The following example illustrates how to calculate the a0 and a1 coefficients for a desired centre  
frequency and -3dB bandwidth.  
fc = 1000 Hz  
fb = 100 Hz  
fs = 48000 Hz  
w0 = 2πfc / fs  
wb = 2πfb / fs  
2π  
2π  
=
=
x (1000 / 48000) = 0.1308996939 rads  
x (100 / 48000) = 0.01308996939 rads  
1tan(wb / 2)  
1+ tan(wb / 2)  
1tan(0.01308996939/ 2)  
a0 =  
1+ tan(0.01308996939/ 2) = 0.9869949627  
=
a1 = −(1+ a0 )cos(w0 )  
(1+ 0.9869949627)cos(0.1308996939)  
=
=
-
1.969995945  
NFA0 = -a0 x 213 = -8085 (rounded to nearest whole number)  
NFA1 = -a1 x 212 = 8069 (rounded to nearest whole number)  
These values are then converted to a 14-bit sign / magnitude notation:  
NFA0[13] = 1; NFA0[12:0] = 13’h1F95; NFA0 = 14’h3F95 = 14’b11111110010101  
NFA1[13] = 0; NFA1[12:0] = 13’h1F85; NFA1 = 14’h1F85 = 14’b01111110000101  
DIGITAL ADC VOLUME CONTROL  
The output of the ADC can be digitally attenuated over a range from –127dB to 0dB in 0.5dB steps.  
The gain for a given eight-bit code X is given by:  
0.5 × (G-255) dB for 1 G 255;  
MUTE for G = 0  
REGISTER  
ADDRESS  
BIT  
LABEL  
DEFAULT  
DESCRIPTION  
R15  
7:0  
ADCVOLL  
[7:0]  
11111111  
( 0dB )  
ADC Digital Volume Control  
0000 0000 = Digital Mute  
0000 0001 = -127dB  
0000 0010 = -126.5dB  
... 0.5dB steps up to  
ADC Digital  
Volume  
1111 1111 = 0dB  
8
ADCVU  
Not  
latched  
ADC volume does not update until a 1 is  
written to ADCVU  
Table 16 ADC Digital Volume Control  
PP Rev 3.0 April 2006  
28  
w
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