WM8900LGEFK/RV Wolfson Microelectronics, WM8900LGEFK/RV Datasheet - Page 46

• Manufacturer Part Number: WM8900LGEFK/RV
• Description: Audio CODECs Ultra Low Power Hi-Fi CODEC
• Manufacturer: Wolfson Microelectronics

Specifications of WM8900LGEFK/RV

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

WM8900
w
DAC SOFT MUTE AND SOFT UN-MUTE
The WM8900 has a soft mute and un-mute function, which, when enabled, gradually attenuates or
amplifies the volume of the DAC output. When the DAC is un-muted 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_MUTEMODE register bit. Conversely, when the DAC is muted the gain will either
gradually ramp down to the digital mute level, or drop instantly to the digital mute level, depending
on the DAC_MUTEMODE register bit setting.
The DAC is muted by default (DAC_MUTE = 1). To play back an audio signal, this function must
first be disabled by setting the DAC_MUTE bit to 0.
Soft Mute Mode would typically be enabled (DAC_MUTEMODE = 1) when using DAC_MUTE
during playback of audio data. When DAC_MUTE is set to logic 0 and the DAC is un-muted, 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).
Soft Mute Mode would typically be disabled (DAC_MUTEMODE = 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).
Figure 17 DAC Mute Control
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 as shown in Table 30. The ramp rate determines the
rate at which the volume will be increased or decreased. The actual ramp time depends on the
extent of the difference between the muted and un-muted volume settings.
PD, August 2008, Rev 4.0
Production Data
46