WM8721(2000) 查看數據表（PDF） - Wolfson Microelectronics plc
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WM8721 Datasheet PDF : 34 Pages
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WM8721
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REGISTER
ADDRESS
0001000
Sampling
Control
BIT
LABEL
0
USB/
NORMAL
1
BOSR
5:2 SR[3:0]
Table 9 Sample Rate Control
DEFAULT
DESCRIPTION
0
Mode Select
1 = USB mode (250/272fs)
0 = Normal mode (256/384fs)
0
Base Over-Sampling Rate
USB Mode
Normal Mode
0 = 250fs
0 = 256fs
1 = 272fs
1 = 384fs
000
DAC sample rate control;
See USB Mode and Normal Mode
Sample Rate sections for operation
NORMAL MODE SAMPLE RATES
In normal mode MCLK is set up according to the desired sample rates of the DAC. For DAC
sampling rates of 8, 32, 48 or 96KHz, MCLK frequencies of either 12.288MHz (256Fs) or 18.432MHz
(384Fs) can be used. DAC sampling rates of 8, 44.1 or 88.2KHz from MCLK frequencies of either
11.2896MHz (250Fs) or 16.9344MHz (384Fs) can be used.
The table below should be used to set up the device to work with the various sample rate
combinations. Refer to Digital Filter Characteristics section for an explanation of the different filter
types.
SAMPLING
RATE
DAC
MCLK
FREQUENCY
SAMPLE
RATE
REGISTER SETTINGS
KHz
MHz
BOSR SR3 SR2 SR1
48
12.288
0
0
0
0
18.432
1
0
0
0
8
12.288
0
0
0
0
18.432
1
0
0
0
32
12.288
0
0
1
1
18.432
1
0
1
1
96
12.288
0
0
1
1
18.432
1
0
1
1
44.1
11.2896
0
1
0
0
16.9344
1
1
0
0
8
(Note 1)
11.2896
16.9344
0
1
1
1
0
0
0
0
88.2
11.2896
0
1
1
1
16.9344
1
1
1
1
Table 10 Normal Mode Sample Rate Look-up Table
SR0
0
0
1
1
0
0
1
1
0
0
1
1
1
1
DIGITAL
FILTER
TYPE
1
1
1
2
1
1
2
Notes:
1. 8k not exact, actual = 8.018kHz
2. All other combinations of BOSR and SR[3:0] that are not in the truth table are invalid
The BOSR bit represents the base over-sampling rate. This is the rate that the WM8721 digital signal
processing is carried out at. In Normal mode, with BOSR = 0, the base over-sampling rate is at
256Fs, with BOSR = 1, the base over-sampling rate is at 384Fs. This can be used to determine the
actual audio data rate required by the DAC.
WOLFSON MICROELECTRONICS LTD
PP Rev 1.3 November 2000
21
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