WM8741
Production Data
VOLUME RAMP MODE
There are two ways to change the volume in the WM8741, 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
44.1
48
1.000
0.726
0.667
0.726
0.667
0.726
0.667
88.2
96
176.4
196
Table 27 Volume Ramp Rates
REGISTER ADDRESS
BIT
LABEL
VOL_
DEFAULT
DESCRIPTION
R4
Volume Control
04h
0
0
Volume ramp mode control:
RAMP
0 = Apply volume change in a single
step.
1 = Ramp between current volume
setting and new volume setting.
Table 28 Volume Ramp Control
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 WM8741, 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
DESCRIPTION
Anti-clipping mode control:
0 = Off, 0dB attenuation
R4
Volume Control
04h
1
ATT2DB
0
1 = On, 2dB attenuation applied
Table 29 Anti-Clipping Digital Attenuation Control
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
DSD_
GAIN
DEFAULT
DESCRIPTION
R8
Mode Control 2
08h
6
0
DSD Plus gain control:
0 = Low gain, 1.4Vrms differential
output level
1 = High gain, 2.0Vrms differential
output level
Table 30 DSD Plus Gain Control
PD, Rev 4.2, October 2009
32
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
