WM8753L
Advanced Information
REGISTER
ADDRESS
BIT
7:0
LABEL
DEFAULT
DESCRIPTION
R16(10h)
Left ADC
Digital Volume
LADCVOL
[7:0]
11000011
( 0dB )
Left ADC Digital Volume Control
0000 0000 = Digital Mute
0000 0001 = -97dB
0000 0010 = -96.5dB
... 0.5dB steps up to
1111 1111 = +30dB
8
LAVU
0
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)
R17 (11h)
7:0
RADCVOL
[7:0]
11000011
( 0dB )
Right ADC Digital Volume Control
0000 0000 = Digital Mute
0000 0001 = -97dB
Right
ADC
Digital Volume
0000 0010 = -96.5dB
... 0.5dB steps up to
1111 1111 = +30dB
8
RAVU
0
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)
=
Table 19 ADC Digital Volume Control
AUTOMATIC LEVEL CONTROL (ALC)
The WM8753L has an automatic level control that aims to keep a constant recording volume
irrespective of the input signal level. This is achieved by continuously adjusting the PGA gain so that
the signal level at the ADC input remains constant. A digital peak detector monitors the ADC output
and changes the PGA gain if necessary.
input
signal
PGA
gain
signal
after
ALC
ALC
target
level
hold decay
time time
attack
time
Figure 10 ALC Operation
AI Rev 3.1 June 2004
31
w
WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
