AK4955 Datasheet, PDF (50/117 Pages) Asahi Kasei Microsystems – 24bit Stereo CODEC with MIC/SPK/Cap-less VIDEO-AMP/ LDO & DSP

[AK4955]
3. The Volume at ALC Operation
The volume value during ALC operation is reflected in VOL7-0 bits. It is possible to check the current volume by reading
the register value of VOL7-0 bits. This function is only enabled in 3-wire control mode (I2C pin = “L”).
VOL7-0 bits
GAIN (dB)
F1H
+36.0
F0H
+35.625
EFH
+35.25
:
:
C5H
+19.5
:
:
92H
+0.375
91H
0.0
90H
−0.375
:
:
2H
−53.625
1H
−54.0
0H
MUTE
Table 35. Value of VOL7-0 bits
4. Example of ALC Setting
Table 36 and Table 37 show the examples of the ALC setting for recording and playback path.
Register Name
LMTH1-0
ZELMN
FRN
ZTM1-0
WTM2-0
IREF7-0
IVL7-0,
IVR7-0
LMAT1-0
LFST
RGAIN1-0
RFST1-0
ALC1
Comment
fs=8kHz
Data
Operation
Limiter detection Level
01
−4.1dBFS
Limiter zero crossing detection
0
Enable
Fast Recovery mode
0
Enable
Zero crossing timeout period
01
32ms
Recovery waiting period
*WTM2-0 bits should be the same
value or larger value than ZTM1-0
001
32ms
bits
Maximum gain at recovery operation E1H
+30dB
Gain of IVOL
E1H
+30dB
Limiter ATT step
00
1 step
Fast Limiter Operation
1
ON
Recovery GAIN step
00
1 step
Fast Recovery Speed
01
4 times
ALC1 enable
1
Enable
Table 36. Example of the ALC Setting (Recording)
fs=48kHz
Data
Operation
01
−4.1dBFS
0
Enable
0
Enable
11
21.3ms
100
42.7ms
E1H
+30dB
E1H
+30dB
00
1 step
1
ON
00
1 step
01
4 times
1
Enable
MS1343-E-00
- 50 -
2011/12