ak4561 AKM Semiconductor, Inc., ak4561 Datasheet - Page 23

• Manufacturer Part Number: ak4561
• Description: 16bit Codec With Built-in Alc And Mic/hp-amp
• Manufacturer: AKM Semiconductor, Inc.

ASAHI KASEI
ALC Mode Control 1
Rev. 0.9
Addr
05H
LMTH: ALC Limiter Detection Level / Recovery Waiting Counter Reset Level
RATT: ALC Recovery GAIN Step
FDATT: FADEIN/OUT ATT Step
LMAT1-0: ALC Limiter ATT Step
ZELM: Enable zero crossing detection at ALC Limiter operation
ALC Mode Control 1
LMTH
RESET
Register Name
0
1
Table 10. ALC Limiter Detection Level / Recovery Waiting Counter Reset Level
0: Disable (RESET)
1: Enable
In case of ZELM = “1”, IPGA of each L/R channel do zero crossing or timeout independently, the
IPGA value is changed by ALC operation. Zero crossing timeout is the same as ALC recovery
operation. In case of ZELM = “0”, the IPGA value is changed immediately.
During the ALC Recovery operation, the number of steps changed from current IPGA value is
set. For example, when the current IPGA value is 30H, RATT = “1” is set, IPGA changes to 32H
by the ALC recovery operation, the input signal level is gained by 1dB (=0.5dB x 2).
When the IPGA value exceeds the reference level (REF6-0), the IPGA value does not increase.
During the FADEIN/OUT operation, the number of steps changed from current IPGA value is
set. For example, when the current IPGA value is 30H, FDATT = “1” is set, IPGA changes to
32H(at FADEIN operation) or 2EH (at FADEOUT operation) by the FADEIN/OUT operation,
the input signal level is changed by 1dB (=0.5dB x 2).
When the IPGA value exceeds the reference level (REF6-0), the IPGA value does not increase.
During the ALC limiter operation, when either Lch or Rch exceeds the ALC limiter detection
level set by LMTH, the number of steps attenuated from current IPGA value is set. For example,
when the current IPGA value is 68H in the state of LMAT1-0 bit = “11”, it becomes IPGA = 64H
by the ALC limiter operation, the input signal level is attenuated by 2dB (=0.5dB x 4).
When the attenuation value exceeds IPGA = “00” (MUTE), it clips to “00”.
ALC Limiter Detection Level
ADC Input
ADC Input -5.0dB
Table 11. ALC Recovery GAIN Step Setting
Table 12. FADEIN/OUT ATT Step Setting
D7
Table 13. ALC Limiter ATT Step Setting
0
0
LMAT1
-3.0dB
0
0
1
1
AKM CONFIDENTIAL
FDATT
RATT
D6
0
0
0
1
0
1
LMAT0
- 23 -
ZELM
0
1
0
1
ALC Recovery Waiting Counter Reset Level
D5
0
GAIN STEP
ATT STEP
-3.0dB > ADC Input
-5.0dB > ADC Input
1
2
1
2
LMAT1 LMAT0 FDATT
ATT STEP
D4
0
1
2
3
4
RESET
RESET
D3
0
RESET
-7.0dB
-5.0dB
D2
0
RATT
D1
0
RESET
[AK4561]
LMTH
2000/09
D0
0