WM8961
Pre-Production
DIGITAL TO ANALOGUE CONVERTER (DAC)
Digital data is passed to the WM8961 via the flexible audio interface to the hi-fi DACs. The digital
audio data is converted to over-sampled bit streams in the on-chip, true 24-bit digital interpolation
filters. The bit-stream data enters two multi-bit, sigma-delta DACs, which convert them to high quality
analogue audio signals. 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 DACs and digital filters are enabled by the DACL and DACR register bits.
REGISTER
ADDRESS
BIT
LABEL
DACL
DEFAULT
DESCRIPTION
R26 (1Ah)
Power
8
0
Left Channel DAC Enable
0 = DAC disabled
Management (2)
1 = DAC enabled
7
DACR
0
Right Channel DAC Enable
0 = DAC disabled
1 = DAC enabled
Table 17 DAC Enable Control
DAC DIGITAL VOLUME CONTROL
The output level (digital volume) 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;
MUTE for X = 0
0dB for 192 ≤ X ≤ 255
The DACVU bit controls the loading of digital volume control data. When DACVU is set to 0, the
LDACVOL or RDACVOL control data will be loaded into the respective control register, but will not
actually change the digital gain setting. Both left and right gain settings are updated when a 1 is
written to DACVU. This makes it possible to update the gain of both channels simultaneously.
See "Volume Updates" section for a description of the volume update function, the zero cross function
and the timeout operation.
REGISTER
ADDRESS
BIT
LABEL
DACVU
DEFAULT
DESCRIPTION
R10 (0Ah)
8
0
DAC Volume Update
Left Channel
Digital Volume
0 = Store LDACVOL in intermediate
latch (no gain change)
1 = Update left and right channel
gains (left = LDACVOL, right =
intermediate latch)
7:0
LDACVOL
[7:0]
11111111
( 0dB )
Left DAC Digital Volume Control
0000 0000 = Digital Mute
0000 0001 = -71.625dB
0000 0010 = -71.250dB
... 0.375dB steps up to
1100 0000 = 0dB
….
1111 1111 = 0dB
(See Table 19 for volume range)
R11 (0Bh)
8
DACVU
0
DAC Volume Update
Right Channel
Digital Volume
0 = Store RDACVOL in intermediate
latch (no gain change)
1 = Update left and right channel
gains (left = intermediate latch, right
= RDACVOL)
7:0
RDACVOL
[7:0]
11111111
( 0dB )
Right DAC Digital Volume Control
similar to LDACVOL
(See Table 19 for volume range)
Table 18 Digital Volume Control
Table 19 shows the DAC Digital Volume Range.
PP, August 2009, Rev 3.1
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
