wm8742 Wolfson Microelectronics plc, wm8742 Datasheet - Page 38

• Manufacturer Part Number: wm8742
• Description: 24-bit 192khz Dac With Advanced Digital Filtering
• Manufacturer: Wolfson Microelectronics plc

WM8742
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It is recommended that the device is muted before the filter response is changed to prevent noise as
the filters are reset from appearing on the outputs.
Full details of these filters are described in Table 68 and Figure 60 to Figure 67.
DSD DIRECT DIGITAL FILTERS
The DSD Direct filters have been designed to provide the minimal of processing to the data with no
decimation, re-quantisation or noise-shaping, in order to preserve the signal integrity as much as
possible.
recommended that whichever DSD Direct filter is chosen it is augmented by analogue post-DAC
filtering in order to adhere to the Scarlet-Book SACD standard.
There are a total of four DSD Direct filter responses available, controlled by two register bits as
described in Table 41 below:
Table 41 DSD Direct Digital Filter Selection
DSD MUTE CONTROL
In DSD Direct mode, an analogue mute can be applied at the output of the DAC. This is controlled by
register bit AMUTE.
Table 42 DSD Analogue Mute Control
POWER SAVING STANDBY CONTROL
Setting the PWDN register bit immediately connects all outputs to V
of the DAC system including the DLL, the audio interface and the DSP. Input data samples are not
preserved, but all control register settings are maintained. When PWDN is cleared the WM8742 will
repeat its power-on initialisation sequence.
Table 43 Powerdown Control
REGISTER ADDRESS
REGISTER ADDRESS
REGISTER ADDRESS
Additional Control 1
Volume Control
Format Control
As a result the filters have a wide bandwidth and a very gradual attenuation.
05h
R32
20h
04h
R5
R4
BIT
BIT
BIT
0
1
7
7
DSD_NO_
AMUTE
LABEL
LABEL
PWDN
NOTCH
LEVEL
LABEL
DSD_
DEFAULT
DEFAULT
DEFAULT
0
0
0
1
DSD Direct mute control:
0 = mute off
1 = mute on
Power Down Mode Select:
0 = Normal Mode
1 = Power Down Mode
DSD Direct 8fs Notch Filter
0: Enable 8fs notch filter
1: Disable 8fs notch filter
DSD Direct Filter Gain
0: High gain
1: Low gain
MID
and resets the digital sections
DESCRIPTION
DESCRIPTION
DESCRIPTION
PD, Rev 4.2,August 2009
Production Data
It is
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