wm8987 Wolfson Microelectronics plc, wm8987 Datasheet - Page 23

• Manufacturer Part Number: wm8987
• Description: Stereo Codec For Portable Audio Applications
• Manufacturer: Wolfson Microelectronics plc

Production Data
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DIGITAL ADC VOLUME CONTROL
The output of the ADCs can be digitally amplified or attenuated over a range from –97dB to +30dB in
0.5dB steps. The volume of each channel can be controlled separately. The gain for a given eight-bit
code X is given by:
0.5 × (X-195) dB for 1 ≤ X ≤ 255;
The LAVU and RAVU control bits control the loading of digital volume control data. When LAVU or
RAVU are set to 0, the LADCVOL or RADCVOL 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 either LAVU or RAVU are set to 1. This makes it possible to update the gain of both
channels simultaneously.
Table 12 ADC Digital Volume Control
R21 (15h)
Left ADC
Digital Volume
R22 (16h)
Right ADC
Digital Volume
REGISTER
ADDRESS
7:0
8
7:0
8
BIT
LADCVOL
[7:0]
LAVU
RADCVOL
[7:0]
RAVU
LABEL
MUTE for X = 0
11000011
( 0dB )
0
11000011
( 0dB )
0
DEFAULT
Left ADC Digital Volume Control
0000 0000 = Digital Mute
0000 0001 = -97dB
0000 0010 = -96.5dB
... 0.5dB steps up to
1111 1111 = +30dB
Left ADC Volume Update
0 = Store LADCVOL in intermediate
latch (no gain change)
1 = Update left and right channel
gains (left = LADCVOL, right =
intermediate latch)
Right ADC Digital Volume Control
0000 0000 = Digital Mute
0000 0001 = -97dB
0000 0010 = -96.5dB
... 0.5dB steps up to
1111 1111 = +30dB
Right ADC Volume Update
0 = Store RADCVOL in intermediate
latch (no gain change)
1 = Update left and right channel
gains (left = intermediate latch, right
= RADCVOL)
DESCRIPTION
PD Rev 4.0 August 2008
WM8987L
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