[AK4634]
3. The Volume at the ALC Operation
The current volume value at the ALC operation is reflected in VOL7-0 bits. It is enable to check the current volume value
by reading the register value of VOL7-0 bits.
This function is available only in 3-wire mode. The volume value at the ALC operation can not be read
in I2C mode.
VOL7-0bits
GAIN(0dB)
F1H
F0H
EFH
:
+36.0
+35.625
+35.25
:
C5H
:
+19.5
:
92H
91H
90H
:
+0.375
0.0
−0.375
:
2H
1H
0H
−53.625
−54.0
MUTE
Table 33. Value of VOL7-0 bits
4. Example of the ALC Operation for Recording Operation
Table 34 shows the examples of the ALC setting for microphone recording.
fs=8kHz
fs=44.1kHz
Operation
Register Name Comment
Data
01
0
Operation
Data
01
0
LMTH1-0
ZELM
Limiter detection Level
−4.1dBFS
Enable
16ms
−4.1dBFS
Enable
23.2ms
Limiter zero crossing detection
Zero crossing timeout period
Recovery waiting period
*WTM1-0 bits should be more than or
equal to ZTM1-0 bits
ZTM1-0
00
01
WTM2-0
000
16ms
011
23.2ms
IREF7-0
IVOL7-0
LMAT1-0
LFST
RGAIN1-0
ALC1
Maximum gain at recovery operation
Gain of IVOL
Limiter ATT step
Fast Limiter Operation
Recovery GAIN step
ALC enable
C5H
C5H
00
1
00
19.5dB
19.5dB
1step
C5H
C5H
00
1
00
19.5dB
19.5dB
1step
ON
ON
1 step
Enable
4 times
1 step
Enable
4times
1
00
1
00
FRSL1-0
Speed of Fast Recovery
Table 34. Example of the ALC Setting (Recording)
MS0983-E-00
2008/07
- 46 -
AKM [ ASAHI KASEI MICROSYSTEMS ]
