WM8904
Pre-Production
ADC OVERSAMPLING RATIO (OSR)
The ADC oversampling rate is programmable to allow power consumption versus audio performance
trade-offs. The default oversampling rate is high for best performance; using the lower OSR setting
reduces ADC power consumption.
To ensure specified ADC performance, the ADC Bias Control bits in register R198 must be set
correctly, depending on the ADC_OSR128 value, as described in Table 14.
REGISTER
ADDRESS
R10 (0Ah)
BIT
LABEL
DEFAULT
DESCRIPTION
ADC_OSR128
ADC Oversampling Ratio
0
1
Analogue
ADC 0
0 = Low Power (64 x fs)
1 = High Performance (128 x fs)
ADC Bias Control (1)
R198 (C6h)
ADC Test 0
ADC_128_OSR
_TST_MODE
2
0
0
0
Set this bit to 1 in ADC 64fs mode
(ADC_OSR128 = 0).
Set this bit to 0 in ADC 128fs mode
(ADC_OSR128 = 1).
ADC_BIASX1P
5
ADC Bias Control (2)
Set this bit to 1 in ADC 64fs mode
(ADC_OSR128 = 0).
Set this bit to 0 in ADC 128fs mode
(ADC_OSR128 = 1).
Table 14 ADC Oversampling Ratio
PP, Rev 3.3, September 2012
52
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
