XWM8739LEFL View Datasheet(PDF) - Wolfson Microelectronics plc
Part Name
Description
MFG CO.
XWM8739LEFL Datasheet PDF : 35 Pages
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WM8739 / WM8739L
Advanced Information
REGISTER
ADDRESS
0001000
Sampling
Control
BIT
0
1
LABEL
USB/
NORMAL
BOSR
5:2
SR[3:0]
Table 7 Sample Rate Control
DEFAULT
DESCRIPTION
0
0
0000
Mode Select
1 = USB mode (250/272fs)
0 = Normal mode (256/384fs)
Base Over-Sampling Rate
USB Mode
Normal Mode
0 = 250fs
0 = 256fs
1 = 272fs
1 = 384fs
ADC sample rate control;
See USB Mode and Normal Mode
Sample Rate sections for operation
NORMAL MODE SAMPLE RATES
In normal mode MCLK/crystal oscillator is set up according to the desired sample rate of the ADC.
For ADC sampling rates of 8, 32, 48 or 96KHz, MCLK frequencies of either 12.288MHz (256fs) or
18.432MHz (384fs) can be used. For ADC sampling rates of 8, 44.1 or 88.2KHz from MCLK
frequencies of either 11.2896MHz (256fs) 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. For example if the user wishes to use the WM8739 in normal mode with the ADC
sample rate at 48KHz, then the device should be programmed with BOSR = 0, SR3 = 0, SR2 = 0,
SR1 = 0 and SR0 = 0 with a 12.288MHz MCLK or with BOSR = 1, SR3 = 0, SR2 = 0, SR1 = 0 and
SR0 = 0 with a 18.432MHz MCLK. The ADC will then operate with a Digital Filter of type 1, refer to
Digital Filter Characteristics section for an explanation of the different filter types.
SAMPLING
RATE
MCLK
FREQUENCY
SAMPLE
RATE
REGISTER SETTINGS
kHz
MHz
BOSR SR3 SR2 SR1 SR0
48
12.288
0
0
0
0
0
18.432
1
0
0
0
0
8
12.288
0
0
0
1
0
18.432
1
0
0
1
0
32
12.288
0
0
1
1
0
18.432
1
0
1
1
0
96
12.288
0
0
1
1
1
18.432
1
0
1
1
1
44.1
11.2896
0
1
0
0
0
16.9344
1
1
0
0
0
8 (Note 1)
11.2896
0
1
0
1
0
16.9344
1
1
0
1
0
88.2
11.2896
0
1
1
1
1
16.9344
1
1
1
1
1
Table 8 Normal Mode Sample Rate Look-up Table
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 WM8739 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 produced by the ADC.
AI Rev 2.2 September 2001
20
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