wm9713 Wolfson Microelectronics plc, wm9713 Datasheet - Page 37

• Manufacturer Part Number: wm9713
• Description: Ac?97 Audio + Touchpanel Codec
• Manufacturer: Wolfson Microelectronics plc

Pre-Production
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When operating in stereo, the peak detector takes the maximum of left and right channel peak
values, and any new gain setting is applied to both left and right PGAs, so that the stereo image is
preserved. However, the ALC function can also be enabled on one channel only. In this case, only
one PGA is controlled by the ALC mechanism, while the other channel runs independently with its
PGA gain set through the control register.
When one ADC channel is unused, the peak detector disregards that channel. The ALC function can
also operate when the two ADC outputs are mixed to mono in the digital domain, but not if they are
mixed to mono in the analogue domain, before entering the ADCs.
Table 14 ALC Control
62h
ALC / Noise
Gate Control
60h
ALC Control
REGISTER
ADDRESS
15:14
13:11
10:9
15:12
11:8
7:4
3:0
BIT
ALCSEL
MAXGAIN
ZCTIMEOUT
ALCL
HLD
DCY
ATK
LABEL
00
(OFF)
111
(+30dB)
11
1011
(-12dB)
0000
(0ms)
0011
(192ms)
0010
(24ms)
DEFAULT
ALC Function Channel Control
00 = ALC disabled
01 = ALC on right channel only
10 = ALC or left channel only
11 = ALC on both left and right channels
ALC PGA Gain Limit Control
000 = -12dB
… (6dB steps)
111 = +30dB
ALC Zero Cross Timeout Delay
Control
00 = 2
01 = 2
10 = 2
11 = 2
Note: Timeout delay values shown
when BITCLK=12.288MHz
ALC Target Level Control
0000 = -28.5dBFS
… (1.5dB steps)
1111 = -6dBFS
Note: This is the target signal level at
the ADC input
ALC Hold Time Control
0000 = 0ms
0001 = 2.67ms
… (time doubles with every step)
1111 = 43.691s
ALC Decay Time Control
0000 = 24ms
… (time doubles with every step)
1010 to 1111 = 24.58s
ALC Attack Time Control
0000 = 6ms
… (time doubles with every step)
1010 to 1111 = 6.14s
14
15
16
17
x t
x t
x t
x t
BITCLK
BITCLK
BITCLK
BITCLK
DESCRIPTION
PP Rev 3.2 September 2008
(1.33ms)
(2.67ms)
(5.33ms)
(10.67ms)
WM9713L
37