ak4141 AKM Semiconductor, Inc., ak4141 Datasheet - Page 26

• Manufacturer Part Number: ak4141
• Description: Nicam/a2/eia-j Digital Stereo Decoder
• Manufacturer: AKM Semiconductor, Inc.

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1. ALC Limiter Operation
During the ALC limiter operation, when either Lch or Rch exceeds the ALC limiter detection level
value (same value for both L and R) is attenuated automatically by the amount defined by the ALC limiter ATT step
(Table
When ZELMN bit = “0” (zero cross detection is enabled), the VOL value is changed by ALC limiter operation at the
individual zero crossing points of Lch and Rch or at the zero crossing timeout. ZTM1-0 bits set the zero crossing timeout
period of both ALC limiter and recovery operation
When ZELMN bit = “1” (zero cross detection is disabled), VOL value is immediately (period: 1/fs) changed by ALC
limiter operation. Attenuation step is fixed to 1 step regardless of the setting of LMAT1-0 bits.
The attenuate operation is executed continuously until the input signal level becomes ALC limiter detection level
11) or less. After completing the attenuate operation, unless ALC bit is changed to “0”, the operation repeats when the
input signal level exceeds LMTH1-0 bits.
MS0952-E-00
ALC Operation
LMTH1
12). The VOL is then set to the same value for both channels.
0
0
1
1
ZTM1
LMAT1
LMTH0 ALC Limiter Detection Level
0
0
1
1
0
0
1
1
0
1
0
1
Table 11. ALC Limiter Detection Level / Recovery Counter Reset Level
ZTM0
LMAT0
ALC Output ≥ −2.5dBFS
ALC Output ≥ −4.1dBFS
ALC Output ≥ −6.0dBFS
ALC Output ≥ −8.5dBFS
0
1
0
1
0
1
0
1
Table 13. ALC Zero Crossing Timeout Period
1024/fs
128/fs
256/fs
512/fs
ALC1 Output
≥ LMTH
Table 12. ALC Limiter ATT Step
1
2
2
1
(Table
16.0ms
32.0ms
32kHz
4.0ms
8.0ms
ALC1 Output
- 26 -
Zero Crossing Timeout Period
13).
ALC1 Limiter ATT Step
ALC Recovery Waiting Counter Reset Level
≥ FS
1
2
4
2
−2.5dBFS > ALC Output ≥ −4.1dBFS
−4.1dBFS > ALC Output ≥ −6.0dBFS
−6.0dBFS > ALC Output ≥ −8.5dBFS
−8.5dBFS > ALC Output ≥ −12dBFS
44.1kHz
11.6ms
23.2ms
2.9ms
5.8ms
ALC1 Output
≥ FS + 6dB
1
2
4
4
10.7ms
21.3ms
48kHz
2.7ms
5.3ms
ALC1 Output
≥ FS + 12dB
1
2
8
8
(default)
(Table
(default)
11), the VOL
(default)
[AK4141]
2008/05
(Table