WM8940
Pre-Production
ALCMIN
000
001
Minimum Gain (dB)
-12
-6
010
0
011
6
100
101
110
111
12
18
24
30
Table 25 ALC Min Gain Values
Note that if the ALC gain setting strays outside the ALC operating range, either by starting the ALC
outside of the range or changing the ALCMAX or ALCMIN settings during operation, the ALC will
immediately adjust the gain to return to the ALC operating range. It is recommended that the ALC
starting gain is set between the ALCMAX and ALCMIN limits.
ALC HOLD TIME (NORMAL MODE ONLY)
In Normal mode, the ALC has an adjustable hold time which sets a time delay before the ALC
begins its decay phase (gain increasing). The hold time is set by the ALCHLD register.
REGISTER
ADDRESS
BIT
LABEL
ALCHLD
DEFAULT
0000
DESCRIPTION
R33
ALC Control 2
Table 26 ALC Hold Time
7:4
ALC hold time before gain is increased.
If the hold time is exceeded this indicates that the signal has reached a new average level and the
ALC will increase the gain to adjust for that new average level. If the signal goes above the
threshold during the hold period, the hold phase is abandoned and the ALC returns to normal
operation.
Pre-Production, Rev 3.0, February 2007
34
w
WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
