WM8978_06 Datasheet, PDF (46/119 Pages) Wolfson Microelectronics plc – Stereo CODEC With Speaker Driver

WM8978
Pre-Production
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 BIT
ADDRESS
LABEL
R32
5:3 ALCMAX
ALC Control 2:0
1
ALCMIN
Table 23 ALC Max/Min Gain
DEFAULT
DESCRIPTION
111
Set Maximum Gain of PGA
000
Set minimum gain of PGA
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 21 ALC Min/Max Gain
ALCMAX
111
110
101
100
011
010
001
000
Maximum Gain (dB)
35.25
29.25
23.25
17.25
11.25
5.25
-0.75
-6.75
Table 24 ALC Max Gain Values
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PP Rev 3.0 May 2006
46