Production Data
WM8776
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
BIT
DEFAULT
DESCRIPTION
LABEL
R12 (0Ch)
0001100
3
ADCOSR
0
ADC oversampling rate select
0: 128x oversampling
ADC Oversampling Rate
1: 64x oversampling
MUTE MODES
Setting MUTE for the DAC will apply a ‘soft’ mute to the input of the digital filters of the channel
muted.
REGISTER ADDRESS
R8 (08h)
BIT
LABEL
DEFAULT
DESCRIPTION
DAC Soft Mute select
0
DMUTE
0
0001000
0 : Normal Operation
1: Soft mute enabled
DAC Mute
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 22 Application and Release of Soft Mute
Figure 22 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 to both
channels 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: 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.
PD Rev 4.0 April 2005
27
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
