ak4642e AKM Semiconductor, Inc., ak4642e Datasheet - Page 38

• Manufacturer Part Number: ak4642e
• Description: Stereo Codec With Mic/hp/spk-amp
• Manufacturer: AKM Semiconductor, Inc.

ASAHI KASEI
3. Example of ALC Operation
Table 27 shows the examples of the ALC setting for mic recording.
The following registers should not be changed during the ALC operation. These bits should be changed after the ALC
operation is finished by ALC bit = “0” or PMADL=PMADR bits = “0”.
MS0420-E-00
Register Name
LMTH
ZELMN
ZTM1-0
WTM1-0
REF7-0
IVL7-0,
IVR7-0
LMAT1-0
RGAIN1-0
ALC
• LMTH, LMAT1-0, WTM1-0, ZTM1-0, RGAIN1-0, REF7-0, ZELMN
WR (LMAT1-0, RGAIN0, ZELMN, LMTH0; ALC= “1”)
WR (ZTM1-0, WTM1-0)
Comment
Limiter detection Level
Limiter zero crossing detection
Zero crossing timeout period
Recovery waiting period
*WTM1-0 bits should be the same data
Maximum gain at recovery operation
Gain of IVOL
Limiter ATT step
Recovery GAIN step
ALC enable
WR (RGAIN1, LMTH1)
as ZTM1-0 bits
Note : WR : Write
WR (IVL/R7-0)
ALC Operation
WR (REF7-0)
Manual Mode
Figure 24. Registers set-up sequence at ALC operation
Table 27. Example of the ALC setting
* The value of IVOL should be
the same or smaller than REF’s
- 38 -
Data
E1H
E1H
01
01
01
00
00
0
1
fs=8kHz
Example:
−4.1dBFS
Operation
Enable
+30dB
+30dB
Enable
1 step
1 step
32ms
32ms
Limiter = Zero crossing Enable
Recovery Cycle = 32ms@8kHz
Limiter and Recovery Step = 1
Maximum Gain = +30.0dB
Limiter Detection Level = −4.1dBFS
ALC bit = “1”
(3) Addr=09H&0CH, Data=E1H
(1) Addr=06H, Data=14H
(2) Addr=08H, Data=E1H
(4) Addr=0BH, Data=00H
(5) Addr=07H, Data=01H
Data
E1H
E1H
01
11
11
00
00
0
1
fs=44.1kHz
Operation
−4.1dBFS
[AK4642EN]
23.2ms
23.2ms
Enable
+30dB
Enable
+30dB
1 step
1 step
2005/09