AK4955 Datasheet, PDF (52/117 Pages) Asahi Kasei Microsystems – 24bit Stereo CODEC with MIC/SPK/Cap-less VIDEO-AMP/ LDO & DSP

[AK4955]
■ Input Digital Volume (Manual Mode)
The input digital volume becomes manual mode when ALC1 bit is set to “0” while ADCPF bit is “1”. This mode is used
in the cases shown below.
1. After exiting reset state, when setting up the registers for ALC operation (ZTM1-0, LMTH and etc.)
2. When the registers for ALC operation (Limiter period, Recovery period and etc.) are changed.
For example; when the sampling frequency is changed.
3. When IVOL is used as a manual volume control.
IVL7-0 and IVR7-0 bits set the gain of the volume control (Table 38). The IVOL value is changed at zero crossing or
timeout. The zero crossing timeout period is set by ZTM1-0 bits. Lch and Rch volumes are set individually by IVL7-0 and
IVR7-0 bits when IVOLC bit = “0”. IVL7-0 bits control both Lch and Rch volumes together when IVOLC bit = “1”.
When changing the volume, zero cross detection is executed on both Lch and Rch independently.
IVL7-0 bits
IVR7-0 bits
GAIN (dB)
Step
F1H
+36.0
F0H
+35.625
EFH
+35.25
:
:
E2H
+30.375
E1H
+30.0
0.375dB
E0H
+29.625
:
:
03H
−53.25
02H
−53.625
01H
−54
00H
MUTE
Table 38. Input Digital Volume Setting
(default)
If IVL7-0 or IVR7-0 bits is written during PMPFIL bit = “0”, IVOL operation starts with the written values after PMPFIL
bit is changed to “1”.
When writing to IVOL7-0 bits continually, take an interval of zero crossing timeout period or more. If not, the zero
crossing counters are reset at each time and the volume will not be changed. However, when writing the same register
values as the previous time, the zero crossing counters will not be reset, so that it could be written in an interval less than
zero crossing timeout.
MS1343-E-00
- 52 -
2011/12