WM8945
Production Data
DAC AUTO-MUTE
The DAC digital mute and volume controls are described earlier in Table 24.
The DAC also incorporates an analogue auto-mute, which is enabled by setting DAC_AUTOMUTE.
When the auto-mute is enabled, and a series of 1024 consecutive zero-samples is detected, the DAC
output is muted in order to attenuate noise that might be present in output signal path. The DAC
resumes normal operation as soon as digital audio data is detected.
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R21 (15h)
DAC_AUTOMUTE
1
DAC Auto-Mute Control
0 = Disabled
4
DAC Control 1
1 = Enabled
Table 26 DAC Auto Mute
Note: The DAC_AUTOMUTE bit should not be set when the BEEP generator is used.
DAC SLOPING STOPBAND FILTER
Two DAC filter types are available, selected by the register bit DAC_SB_FLT. When operating at
lower sample rates (e.g. during voice communication) it is recommended that the sloping stopband
filter type is selected (DAC_SB_FLT=1) to reduce out-of-band noise which can be audible at low DAC
sample rates. See “Digital Filter Characteristics” for details of DAC filter characteristics.
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R22 (16h)
DAC_SB_FLT
0
Selects DAC filter characteristics
0 = Normal mode
0
DAC Control 2
1 = Sloping stopband mode
Table 27 DAC Sloping Stopband Filter
PD, May 2011, Rev 4.1
48
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