Production Data
WM8955BL
DIGITAL VOLUME CONTROL
The WM8955BL has on-chip digital attenuation from –127dB to 0dB in 0.5dB steps, allowing the user
to adjust the volume of each channel separately. The level of attenuation for an eight-bit code X is
given by:
-0.5 × (255 – X) dB for 1 ≤ X ≤ 255;
MUTE for X = 0
The LDVU and RDVU control bits control the loading of digital volume control data. When LDVU or
RDVU are set to 0, the LDACVOL or RDACVOL control data is loaded into an intermediate register,
but the actual gain does not change. Both left and right gain settings are updated simultaneously
when either LDVU or RDVU are set to 1.
REGISTER
ADDRESS
BIT
7:0
LABEL
DEFAULT
DESCRIPTION
R10 (0Ah)
LDACVOL[7:0]
11111111
( 0dB )
Left DAC Digital Volume Control
0000 0000 = Digital Mute
0000 0001 = -127dB
Left Channel
Digital Volume
0000 0010 = -126.5dB
... 0.5dB steps up to
1111 1111 = 0dB
8
LDVU
0
Left DAC Volume Update
0 = Store LDACVOL in intermediate
latch (no gain change)
1 = Update left and right channel
gains (left = LDACVOL, right =
intermediate latch)
R11 (0Bh)
7:0
8
RDACVOL[7:0]
RDVU
11111111
( 0dB )
0
Right DAC Digital Volume Control
similar to LDACVOL
Right Channel
Digital Volume
Right DAC Volume Update
0 = Store RDACVOL in intermediate
latch (no gain change)
1 = Update left and right channel
gains (left = intermediate latch,
right = RDACVOL)
Table 3 Digital Volume Control
PD Rev 4.1 February 2007
17
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
