AK4636 Datasheet, PDF (56/105 Pages) Asahi Kasei Microsystems – 16-Bit Mono CODEC with ALC & MIC/SPK/Video-AMP

[AK4636]
ZTM1 bit
0
0
1
1
ZTM0 bit
Zero Cross Timeout Period
8kHz
16kHz
44.1kHz
0
128/fs
16ms
8ms
2.9ms
1
256/fs
32ms
16ms
5.8ms
0
512/fs
64ms
32ms
11.6ms
1
1024/fs
128ms
64ms
23.2ms
Table 29. ALC Zero Cross Timeout Period Settings
(default)
(2) Noise Level Hold
During the waiting time set by WTM2-0 bits (Table 3), VOL values are kept when the input signal peak level is in
between the set value of NSTHH1-0 (Note 37) and Noise Suppression Threshold Low Level (Noise Suppression High
Level >input signal level ≥ Noise Suppression Threshold Low Level) therefore the output signal level does not change.
NSTHH1 bit NSTHH0 bit Noise Suppression High Level (Note 37)
0
0
NSTHL3-0bits + 3dB
0
1
NSTHL3-0bits + 6dB
(default)
1
0
NSTHL3-0bits + 9dB
1
1
NSTHL3-0bits + 12dB
Note 37. Noise Suppression Threshold Low Level (NSTHL3-0 bits) + Gain (NSTHH1-0 bits) = Noise Suppression High
Level
Table 40. Noise Suppression High Level Settings
(3) Noise Suppression → Normal ALC Operation
During noise suppressing operation, if the input signal level exceeds Noise Suppression High Level, the operation
switches to normal ALC operation from noise suppressing or noise level hold operation. In this case, recovery speed is
faster than the normal recovery. (Table 41)
When the internal volume level is lower than noise suppressing operation reference level (set by NSREF7-0 bits), the
recovery speed to ALC operation from noise suppressing operation is the same as normal ALC recovery speed.
NSGAIN1 bit
NSGAIN0 bit
Recovery Speed
0
0
8 step
0
1
12 step
(default)
1
0
16 step
1
1
28 step
Table 41. Fast Recovery Speed Setting from Noise Suppression to ALC Operation
MS1012-E-01
- 56 -
2010/08