AK4640_05 AKM [Asahi Kasei Microsystems], AK4640_05 Datasheet - Page 31

• Manufacturer Part Number: AK4640_05
• Description: 16-Bit ?? CODEC with MIC/HP/SPK-AMP
• Manufacturer: AKM [Asahi Kasei Microsystems]

ASAHI KASEI
(3) Example of ALC1 Operation
Table 15 shows the examples of the ALC1 setting. In case of this examples, ALC1 operation starts from 0dB.
The following registers should not be changed during the ALC1 operation. These bits should be changed after the ALC1
operation is finished by ALC1 bit = “0” or PMMIC bit = “0”.
IPGA gain at ALC1 operation start can be changed from the default value of IPGA6-0 bits while PMMIC bit is “1” and
ALC1 bit is “0”. When ALC1 bit is changed from “1” to “0”, IPGA holds the last gain value set by ALC1 operation.
MS0273-E-02
Register Name Comment
LMTH
LTM1-0
ZELM
ZTM1-0
WTM1-0
REF6-0
IPGA6-0
LMAT1-0
RATT
ALC1
• LTM1-0, LMTH, LMAT1-0, WTM1-0, ZTM1-0, RATT, REF6-0, ZELM bits
WR (ALC1= “1”, LMAT1-0, RATT, LMTH, ZELM)
WR (ZTM1-0, WTM1-0, LTM1-0)
Limiter detection Level
Limiter operation period at ZELM = 1
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 IPGA before ALC1 operation
start
Limiter ATT Step
Recovery GAIN Step
ALC1 Enable bit
as ZTM1-0 bits
Note : WR : Write
ALC1 Operation
WR (IPGA6-0)
Manual Mode
WR (REF6-0)
Figure 20. Registers set-up sequence at ALC1 operation
* The value of IPGA should be
Table 15. Example of the ALC1 setting
the same or smaller than REF’s
- 31 -
Data
47H
10H
00
00
00
00
1
0
0
1
fs=8kHz
Don’t use
Operatio
+27.5dB
−4dBFS
Enable
Enable
1 step
1 step
16ms
16ms
0dB
n
Example:
Limiter = Zero crossing Enable
Recovery Cycle = 16ms @ fs= 8kHz
Limiter and Recovery Step = 1
Maximum Gain = +27.5dB
Limiter Detection Level = -4dBFS
ALC2 bit = “1” (default)
Data
47H
10H
00
01
01
00
1
0
0
1
(1) Addr=08H, Data=00H
(2) Addr=0AH, Data=47H
(3) Addr=0BH, Data=10H
(4) Addr=09H, Data=61H
fs=16kHz
Don’t use
Operatio
+27.5dB
−4dBFS
Enable
Enable
1 step
1 step
16ms
16ms
0dB
n
Data
47H
10H
10
10
00
00
1
0
1
0
fs=44.1kHz
Don’t use
Operatio
+27.5dB
−4dBFS
11.6ms
11.6ms
Enable
Enable
1 step
1 step
[AK4640]
0dB
n
2005/04