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WM8774
ADC OVERSAMPLING RATE SELECT
For ADC operation at 96kHz, it is recommended that the user set the ADCOSR bit. This changes the
ADC signal processing oversample rate to 64fs.
REGISTER ADDRESS
10111
BIT
LABEL
DEFAULT
DESCRIPTION
ADC oversampling rate select
0: 128x oversampling
3
ADCOSR
0
ADC Oversampling Rate
1: 64x oversampling
MUTE MODES
Setting DMUTE will apply a ‘soft’ mute to the input of the DAC digital filters.
REGISTER ADDRESS
10100
BIT
LABEL
DEFAULT
DESCRIPTION
DAC Soft Mute select
0
DMUTE
0
DAC Mute
0 : Normal Operation
1: Soft mute enabled
1.5
1
0.5
0
-0.5
-1
-1.5
-2
-2.5
0
0.001
0.002
0.003
0.004
0.005
0.006
Time(s)
Figure 17 Application and Release of Soft Mute
Figure 17 shows the application and release of DMUTE whilst a full amplitude sinusoid is being
played at 48kHz sampling rate. When DMUTE (lower trace) is asserted, the output (upper trace)
begins to decay exponentially from the DC level of the last input sample. The output will decay
towards VMID with a time constant of approximately 64 input samples. If DMUTE is applied for 1024
or more input samples, the DAC will be muted if IZD is set. When DMUTE is de-asserted, the output
will restart immediately from the current input sample.
Note that all other means of muting the DAC channels: setting the PL[3:0] bits to 0, setting the
PDWN bit or setting attenuation to 0 will cause much more abrupt muting of the output.
PP Rev 1.0 June 2002
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
