WM8955BL Wolfson Microelectronics, WM8955BL Datasheet - Page 17

• Manufacturer Part Number: WM8955BL
• Description: Stereo DAC
• Manufacturer: Wolfson Microelectronics

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Production Data
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;
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.
Table 3 Digital Volume Control
R10 (0Ah)
Left Channel
Digital Volume
R11 (0Bh)
Right Channel
Digital Volume
REGISTER
ADDRESS
7:0
8
7:0
8
BIT
LDACVOL[7:0]
LDVU
RDACVOL[7:0]
RDVU
LABEL
MUTE for X = 0
11111111
( 0dB )
0
11111111
( 0dB )
0
DEFAULT
Left DAC Digital Volume Control
0000 0000 = Digital Mute
0000 0001 = -127dB
0000 0010 = -126.5dB
... 0.5dB steps up to
1111 1111 = 0dB
Left DAC Volume Update
0 = Store LDACVOL in intermediate
1 = Update left and right channel
Right DAC Digital Volume Control
similar to LDACVOL
Right DAC Volume Update
0 = Store RDACVOL in intermediate
1 = Update left and right channel
latch (no gain change)
gains (left = LDACVOL, right =
intermediate latch)
latch (no gain change)
gains (left = intermediate latch,
right = RDACVOL)
DESCRIPTION
PD Rev 4.1 February 2007
WM8955BL
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