ak4647 AKM Semiconductor, Inc., ak4647 Datasheet - Page 35

• Manufacturer Part Number: ak4647
• Description: Stereo Codec With Mic/hp-amp
• Manufacturer: AKM Semiconductor, Inc.

ASAHI KASEI
3. Example of ALC Operation
Table 29 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”.
MS0566-E-00
Register Name
LMTH1-0
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, WTM2-0)
WR (RGAIN1, LMTH1)
Comment
Limiter detection Level
Limiter zero crossing detection
Zero crossing timeout period
Recovery waiting period
*WTM1-0 bits should be the same or
Maximum gain at recovery operation
Gain of IVOL
Limiter ATT step
Recovery GAIN step
ALC enable
WR (IVL/R7-0)
ALC Operation
longer data as ZTM1-0 bits.
WR (REF7-0)
Note : WR : Write
Manual Mode
Figure 25. Registers set-up sequence at ALC operation
* The value of IVOL should be
the same or smaller than REF’s
Table 29. Example of the ALC setting
- 35 -
Data
E1H
E1H
01
01
01
00
00
0
1
Example:
Limiter = Zero crossing Enable
Recovery Cycle = 32ms@8kHz
Zero Crossing Timeout Period = 32ms@8kHz
Limiter and Recovery Step = 1
Gain of IVOL = +30dB
Maximum Gain = +30.0dB
Limiter Detection Level = −4.1dBFS
ALC bit = “1”
fs=8kHz
−4.1dBFS
Operation
Enable
+30dB
+30dB
Enable
1 step
1 step
32ms
32ms
(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=21H
Data
E1H
E1H
01
11
11
00
00
0
1
fs=44.1kHz
Operation
−4.1dBFS
23.2ms
23.2ms
Enable
+30dB
Enable
+30dB
1 step
1 step
[AK4647]
2006/11