ASAHI KASEI
[AK4644]
Input Digital Volume (Manual Mode)
The input digital volume becomes a manual mode when ALC bit is “0”. This mode is used in the case shown below.
1. After exiting reset state, set-up the registers for the ALC operation (ZTM1-0, LMTH1-0 and etc)
2. When the registers for the ALC operation (Limiter period, Recovery period and etc) are changed.
For example; when the change of the sampling frequency.
3. When IVOL is used as a manual volume.
IVL7-0 and IVR7-0 bits set the gain of the volume control (Table 36). The IVOL value is changed at zero crossing or
timeout. Zero crossing timeout period is set by ZTM1-0 bits. If IVL7-0 or IVR7-0 bits are written during
PMADL=PMADR bits = “0”, IVOL operation starts with the written values at the end of the ADC initialization cycle
after PMADL or PMADR bit is changed to “1”.
Even if the path is switched from recording to playback, the register setting of IVOL remains. Therefore, IVL7-0 and
IVR7-0 bits should be set to “91H” (0dB).
IVL7-0
IVR7-0
GAIN (dB)
Step
F1H
F0H
EFH
:
+36.0
+35.625
+35.25
:
E2H
E1H
E0H
:
+30.375
+30.0
+29.625
:
0.375dB
Default
03H
02H
01H
00H
−53.25
−53.625
−54
MUTE
Table 36. Input Digital Volume Setting
MS0477-E-01
2006/10
- 46 -
AKM [ ASAHI KASEI MICROSYSTEMS ]
