WM8940
Pre-Production
DESCRIPTION
REGISTER
ADDRESS
BIT
7:4
LABEL
ALCHLD
DEFAULT
0000
(0ms)
ALC hold time before gain is increased.
0000 = 0ms
[3:0]
0001 = 2.67ms
0010 = 5.33ms
0011 = 10.66ms
0100 = 21.32ms
0101 = 42.64ms
0110 = 85.28ms
0111 = 0.17s
1000 = 0.34s
1001 = 0.68s
1010 or higher = 1.36s
Determines the ALC mode of operation:
0 = ALC mode (Normal Operation)
1 = Limiter mode.
R34 (22h)
8
ALCMODE
0
ALC Control 3
7:4
ALCDCY
[3:0]
0011
Decay (gain ramp-up) time
(ALCMODE ==0)
(26ms/6dB)
Per step Per 6dB 90% of
range
0000
0001
0010
410us
820us
1.64ms
3.38ms
6.56ms
13.1ms
23.6ms
47.2ms
94.5ms
… (time doubles with every step)
1010
or
420ms
3.36s
24.2s
higher
0011
Decay (gain ramp-up) time
(ALCMODE ==1)
(5.8ms/6dB)
Per step Per 6dB 90% of
range
0000
0001
0010
90.8us
182us
363us
726us
5.23ms
10.5ms
20.9ms
1.45ms
2.91ms
… (time doubles with every step)
1010 93ms 744ms 5.36s
3:0
ALCATK
[3:0]
0010
ALC attack (gain ramp-down) time
(ALCMODE == 0)
(3.3ms/6dB)
Per step Per 6dB 90% of
range
0000
0001
0010
104us
208us
416us
832us
1.66ms
3.33ms
6ms
12ms
24ms
… (time doubles with every step)
1010 or 106ms
higher
852ms
6.13s
0010
ALC attack (gain ramp-down) time
(ALCMODE == 1)
(726us/6dB)
Per step Per 6dB 90% of
range
0000
0001
0010
22.7us
45.4us
90.8us
182.4us 1.31ms
363us
726us
2.62ms
5.23ms
… (time doubles with every step)
Pre-Production, Rev 3.0, February 2007
28
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
