wm9081 Wolfson Microelectronics plc, wm9081 Datasheet - Page 43

• Manufacturer Part Number: wm9081
• Description: Mono Dac With 2.6w Class Ab/d Speaker Driver, Dynamic Range Controller And Retune Mobile Parametric Equalizer
• Manufacturer: Wolfson Microelectronics plc

Pre-Production
DIGITAL TO ANALOGUE CONVERTER (DAC)
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The WM9081 DAC receives digital input data from the DACDAT pin. The digital audio data is
converted to oversampled bit streams in the on-chip, true 24-bit digital interpolation filters. The
bitstream data enters a multi-bit, sigma-delta DAC, which converts it to a high quality analogue audio
signal. The multi-bit DAC architecture reduces high frequency noise and sensitivity to clock jitter. It
also uses a Dynamic Element Matching technique for high linearity and low distortion.
The analogue outputs from the DAC can then be mixed with other analogue inputs using the
analogue mixer and can be output to the speaker amplifier or the line output.
The DAC is enabled by the DAC_ENA register bit.
Table 22 DAC Enable Control
DAC DIGITAL VOLUME CONTROL
The output level of each DAC can be controlled digitally over a range from -71.625dB to 0dB in
0.375dB steps. The level of attenuation for an eight-bit code X is given by:
0.375 × (X-192) dB for 1 ≤ X ≤ 192;
Table 23 DAC Digital Volume Control
DAC SOFT MUTE AND SOFT UN-MUTE
The WM9081 has a soft mute function which, when enabled, gradually attenuates the volume of the
DAC output. 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 DAC_MUTEMODE
register bit.
The DAC is soft-muted by default (DAC_MUTE = 1). To play back an audio signal, this function must
first be disabled by setting DAC_MUTE to 0.
Soft Mute Mode would typically be enabled (DAC_MUTEMODE = 1) when using DAC_MUTE during
playback of audio data so that when DAC_MUTE is subsequently disabled, the sudden volume
increase will not create pop noise by jumping immediately to the previous volume level (e.g.
resuming playback after pausing).
R11 (0Bh)
Power
Management
R30 (1Eh)
DAC Digital 1
REGISTER
REGISTER
ADDRESS
ADDRESS
0
7:0
BIT
BIT
DAC_ENA
DAC_VOL
[7:0]
LABEL
LABEL
MUTE for X = 0
0
1100_
0000
DEFAULT
DEFAULT
DAC Enable
0dB for 192 ≤ X ≤ 255
0 = Disabled
1 = Enabled
DAC Volume and MUTE
0000 0000 = MUTE
0000 0001 = -71.625dB
… in steps of 0.375dB to
1100 0000 = 0dB
1100 0001 to 1111 1111 = reserved
DESCRIPTION
DESCRIPTION
PP, Rev 3.0, April 2009
WM9081
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