AK4650 Datasheet, PDF (31/86 Pages) Asahi Kasei Microsystems – 16Bit ΔΣ CODEC with MIC/HP/SPK-AMP & TSC

[AK4650]
(3) Example of ALC1 Operation
Table 22 shows the examples of the ALC1 setting. In case of this examples, ALC1 operation starts from 0dB.
Register
Name
LMTH
LTM1-0
ZELMN
ZTM1-0
WTM1-0
REF5-0
IPGA5-0
LMAT1-0
RGAIN
ALC1
Comment
fs=8kHz
fs=16kHz
Data Operation Data Operation
Limiter detection Level
1
−4dBFS
1
−4dBFS
Limiter operation period at ZELMN 00 Don’t use 00 Don’t use
bit = “1”
Limiter zero crossing detection
0
Enable
0
Enable
Zero crossing timeout period
00
16ms
01
16ms
Recovery waiting period
*WTM1-0 bits should be the same 00
16ms
01
16ms
data as ZTM1-0 bits
Maximum gain at recovery operation 3DH +26.5dB 3DH +26.5dB
Gain of IPGA at ALC1 operation start 37H
0dB
37H
0dB
Limiter ATT Step
00
0.5dB
00
0.5dB
Recovery GAIN Step
0
0.5dB
0
0.5dB
ALC1 Enable bit
1
Enable
1
Enable
Table 22. Example of the ALC1 setting
fs=44.1kHz
Data Operation
1
−4dBFS
00 Don’t use
0
Enable
10
11.6ms
10
11.6ms
3DH +26.5dB
37H
0dB
00
0.5dB
0
0.5dB
1
Enable
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”.
• LTM1-0, LMTH, LMAT1-0, WTM1-0, ZTM1-0, RGAIN, REF5-0, ZELMN bits
IPGA gain at ALC1 operation start can be changed from the default value of IPGA5-0 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.
Manual Mode
Example:
Limiter = Zero crossing Enable
Recovery Cycle = 16ms @ fs= 8kHz
Limiter and Recovery Step = 0.5dB
Maximum Gain = +26.5dB
Limiter Detection Level = −4dBFS
ALC bit = “1”
WR (ZTM1-0, WTM1-0, LTM1-0)
(1) Addr=66H, Data=4100H
WR (REF5-0)
WR (IPGA5-0) ^{* The value of IPGA should be}
the same or smaller than REF’s
WR (ALC1= “1”, LMAT1-0, RGAIN, LMTH, ZELMN)
(2) Addr=64H, Data=3D31H
(3) Addr=0EH, Data=0077H
(4) Addr=66H, Data=6100H
ALC1 Operation
Note : WR : Write
Figure 19. Registers set-up sequence at ALC1 operation
MS0502-E-01
- 31 -
2007/04