WM8741 datasheet(33/63 Pages) WOLFSON

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WM8741

PP Rev 1.3 October 2007

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)

1.000

44.1

0.726

0.667

88.2

0.726

0.667

176.4

0.726

196

0.667

Table 27 Volume Ramp Rates

BIT

LABEL

DEFAULT

DESCRIPTION

Volume Control

04h

VOL_

RAMP

Volume ramp mode control:

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.

BIT

LABEL

DEFAULT

DESCRIPTION

Volume Control

04h

ATT2DB

Anti-clipping mode control:

0 = Off, 0dB attenuation

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.

BIT

LABEL

DEFAULT

DESCRIPTION

Mode Control 2

08h

DSD_

GAIN

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

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