WM8961 datasheet(38/116 Pages) WOLFSON

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WM8961

Pre-Production

PP, August 2009, Rev 3.1

DAC SOFT MUTE AND SOFT UN-MUTE

The WM8961 also has a soft mute function, which, when enabled, gradually attenuates the volume of

the digital signal to zero. When soft mute is disabled, the gain will either gradually ramp back up to the

digital gain setting, or return instantly to the digital gain setting, depending on the DACSMM register

bit.

The DAC is soft-muted by default. To play back an audio signal, this function must first be disabled by

setting the DACMU bit to zero.

DACSMM would typically be enabled when using soft mute during playback of audio data so that

when soft mute is then disabled, the sudden volume increase will not create pop noise by jumping

immediately to the previous volume level (e.g. resuming playback after pausing during a track).

DACSMM would typically be disabled when un-muting at the start of a digital music file, so that the

first part of the track is not attenuated (e.g. when starting playback of a new track, or resuming

playback after pausing between tracks).

DAC muting and un-muting using

volume control bits LDACVOL and

RDACVOL.

DAC muting and un-muting using soft

mute bit DACMU.

Soft un-mute not enabled (DACSMM

= 0).

DAC muting and un-muting using soft

mute bit DACMU.

Soft un-mute enabled (DACSMM =

1).

Figure 17 DAC Mute Control

The volume ramp rate during soft mute and un-mute is controlled by the DACMR bit. Ramp rates of

fs/32 and fs/2 are selectable as shown in Table 20 (fs = DAC sample rate).

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

R5 (05h)

ADC and DAC

Control (1)

DACMU

Digital Soft Mute

1 = Mute

0 = No mute (signal active)

R6 (06h)

ADC and DAC

Control (2)

DACSMM

DAC Soft Mute Mode

0 = Disabling soft-mute (DACMU=0)

will cause the volume to change

immediately to the LDACVOL /

RDACVOL settings

1 = Disabling soft-mute (DACMU=0)

will cause the volume to ramp up

gradually to the LDACVOL /

RDACVOL settings

DACMR

DAC Soft Mute Ramp Rate

0 = Fast ramp (fs/2 at fs=48k,

providing maximum delay of 10.7ms)

1 = Slow ramp (fs/32 at fs=48k,

providing maximum delay of

171ms)DAC Soft Mute Ramp Rate

Table 20 DAC Soft-Mute Control

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