Pre-Production
WM8940
MINIMUM AND MAXIMUM GAIN
The ALCMIN and ALCMAX register bits set the minimum/maximum gain value that the PGA can be
set to whilst under the control of the ALC. This has no effect on the PGA when ALC is not enabled.
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R32
5:3
2:0
Table 23 ALC Max/Min Gain
ALCMAX
111
000
Set Maximum Gain of PGA
Set minimum gain of PGA
ALC Control 1
ALCMIN
In normal mode, ALCMAX sets the maximum boost which can be applied to the signal. In limiter
mode, ALCMAX will normally have no effect (assuming the starting gain value is less than the
maximum gain specified by ALCMAX) because the maximum gain is set at the starting gain level.
ALCMIN sets the minimum gain value which can be applied to the signal.
Figure 14 ALC Min/Max Gain
ALCMAX
111
110
101
100
Maximum Gain (dB)
35.25
29.25
23.25
17.25
11.25
5.25
011
010
001
000
-0.75
-6.75
Table 24 ALC Max Gain Values
Pre-Production, Rev 3.0, February 2007
33
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
