WM1811A datasheet(67/328 Pages) WOLFSON

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WM1811A

PD, November 2013, Rev 4.1

DIGITAL VOLUME SOFT MUTE AND SOFT UN-MUTE

The WM1811A has a soft mute function which ensures that a gradual attenuation is applied to the

DAC output mixers or AIF2 output mixers when the associated mute is asserted. The soft mute rate

can be selected using the DAC_MUTERATE bit.

When a mute bit 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 DAC_SOFTMUTEMODE register bit. If the

gradual un-mute ramp is selected (DAC_SOFTMUTEMODE = 1), then the un-mute rate is determined

by the DAC_MUTERATE bit.

Note that each DAC (or AIF2 output mixer) is soft-muted by default. To play back an audio signal, the

mute must first be disabled by setting the applicable mute control to 0 (seeTable 21).

Soft Mute Mode would typically be enabled (DAC_SOFTMUTEMODE = 1) when using mute during

playback of audio data so that when the mute is subsequently disabled, the volume increase will not

create pop noise by jumping immediately to the previous volume level (e.g. resuming playback after

pausing during a track).

Soft Mute Mode would typically be disabled (DAC_SOFTMUTEMODE = 0) when un-muting at the

start of a music file, in order 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).

The DAC soft-mute function is illustrated in Figure 19 for DAC1L and DAC1R. The same function is

applicable to AIF2TXL and AIF2TXRalso.

= 00000000

= [non-zero]

DAC1L_MUTE = 0

DAC1R_MUTE = 0

DAC1L_MUTE = 1

DAC1R_MUTE = 1

DAC1L_MUTE = 0

DAC1R_MUTE = 0

DAC1L_MUTE = 0

DAC1R_MUTE = 0

DAC1L_MUTE = 1

DAC1R_MUTE = 1

DAC1L_MUTE = 0

DAC1R_MUTE = 0

DAC1L_VOL or DAC1R_VOL = [non-zero]

DAC_SOFTMUTEMODE = 0

DAC_SOFTMUTEMODE = 1

DAC muting and un-muting using volume control bits

DAC1L_VOL and DAC1R_VOL

DAC muting and un-muting using soft mute bits

DAC1L_MUTE or DAC1R_MUTE

Soft mute mode not enabled (DAC_SOFTMUTEMODE = 0).

DAC muting and un-muting using soft mute bit DAC_MUTE.

Soft mute mode enabled (DAC_SOFTMUTEMODE = 1).

Figure 19 Digital Volume Soft Mute Control

The DAC Soft Mute register controls are defined in Table 23.

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

rates of fs/32 and fs/2 are selectable. The ramp rate determines the rate at which the volume will be

increased or decreased. Note that the actual ramp time depends on the extent of the difference

between the muted and un-muted volume settings.

WM1811A Datasheet(PDF) 67 Page - Wolfson Microelectronics plc

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