wm8961 Wolfson Microelectronics plc, wm8961 Datasheet - Page 36

• Manufacturer Part Number: wm8961
• Description: Ultra-low Power Stereo Codec With 1w Stereo Class D Speaker Drivers And Ground Referenced Headphone Drivers
• Manufacturer: Wolfson Microelectronics plc

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WM8961
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.
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;
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.
Table 18 Digital Volume Control
Table 19 shows the DAC Digital Volume Range.
R26 (1Ah)
Power
Management (2)
R10 (0Ah)
Left Channel
Digital Volume
R11 (0Bh)
Right Channel
Digital Volume
REGISTER
ADDRESS
REGISTER
ADDRESS
8
7:0
8
7:0
BIT
8
7
BIT
LDACVOL
DACVU
[7:0]
DACVU
RDACVOL
[7:0]
DACL
DACR
LABEL
LABEL
MUTE for X = 0
0
0
DEFAULT
0
11111111
( 0dB )
0
11111111
( 0dB )
DEFAULT
Left Channel DAC Enable
0 = DAC disabled
1 = DAC enabled
Right Channel DAC Enable
0 = DAC disabled
1 = DAC enabled
0dB for 192 ≤ X ≤ 255
DAC Volume Update
0 = Store LDACVOL in intermediate
latch (no gain change)
1 = Update left and right channel
gains (left = LDACVOL, right =
intermediate latch)
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)
DAC Volume Update
0 = Store RDACVOL in intermediate
latch (no gain change)
1 = Update left and right channel
gains (left = intermediate latch, right
= RDACVOL)
Right DAC Digital Volume Control
similar to LDACVOL
(See Table 19 for volume range)
DESCRIPTION
DESCRIPTION
PP, August 2009, Rev 3.1
Pre-Production
36