WM8742 View Datasheet(PDF) - Cirrus Logic
Part Name
Description
MFG CO.
'WM8742' PDF : 65 Pages View PDF
WM8742
Production Data
VOLUME RAMP MODE
There are two ways to change the volume in the WM8742, controlled by VOL_RAMP. When
VOL_RAMP=0, the volume changes in a single step from the current volume setting to the new
volume when an update is applied to the gain control registers. When VOL_RAMP=1, the volume is
automatically ramped from the current volume setting to the new volume setting when an update is
applied to the volume control registers. The speed at which this happens is dependant on the sample
rate as shown in Table 27 below:
SAMPLE RATE (kHz)
RAMP RATE (ms/dB)
32
1.000
44.1
0.726
48
0.667
88.2
0.726
96
0.667
176.4
0.726
196
0.667
Table 27 Volume Ramp Rates
REGISTER ADDRESS BIT
R4
0
Volume Control
04h
Table 28 Volume Ramp Control
LABEL
VOL_
RAMP
DEFAULT
0
DESCRIPTION
Volume ramp mode control:
0 = Apply volume change in a single
step.
1 = Ramp between current volume
setting and new volume setting.
ANTI-CLIPPING DIGITAL ATTENUATION MODE
Audio material is regularly recorded up to 0dB level and heavily compressed. This may cause
clipping and occasional distortion when the digital media is applied to a DAC. In order to prevent this
in the WM8742, an anti-clipping mode is provided, which attenuates the digital signal by 2dB as it is
processed through the digital filters.
REGISTER ADDRESS BIT LABEL DEFAULT
R4
Volume Control
04h
1 ATT2DB
0
Table 29 Anti-Clipping Digital Attenuation Control
DESCRIPTION
Anti-clipping mode control:
0 = Off, 0dB attenuation
1 = On, 2dB attenuation applied
DSD PLUS GAIN CONTROL
The gain in the DSD Plus data path can be adjusted. The default setting provides a 1.4Vrms
differential output level.
REGISTER ADDRESS BIT LABEL
R8
6
DSD_
Mode Control 2
GAIN
08h
Table 30 DSD Plus Gain Control
DEFAULT
0
DESCRIPTION
DSD Plus gain control:
0 = Low gain, 1.4Vrms differential
output level
1 = High gain, 2.0Vrms differential
output level
w
PD, Rev 4.3, February 2013
32
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