AK4951AEN Datasheet, PDF (51/105 Pages) Asahi Kasei Microsystems – 24bit Stereo CODEC with MIC/HP/SPK-AMP

[AK4951A]
1. ALC Limiter Operation
During ALC limiter operation, when either L or R channel output level exceeds the ALC limiter detection
level (Table 35), the VOL value (same value for both L and R) is attenuated automatically by the amount
defined by the ALC limiter ATT step (Table 36). (Once this ALC limiter operation is started, attenuation will
be repeated sixteen times.)
After completing the attenuate operation, unless ALC bit is changed to “0”, the operation repeats when
the input signal level exceeds ALC limiter detection level.
Table 35. ALC Limiter Detection Level/ Recovery Counter Reset Level
LMTH2
bit
LMTH1
bit
LMTH0
bit
ALC Limiter Detection Level
ALC Recovery Counter Reset Level
0
0
0
ALC Output  2.5dBFS 2.5dBFS > ALC Output  4.1dBFS (default)
0
0
1
ALC Output  2.5dBFS 2.5dBFS > ALC Output  3.3dBFS
0
1
0
ALC Output  4.1dBFS 4.1dBFS > ALC Output  6.0dBFS
0
1
1
ALC Output  4.1dBFS 4.1dBFS > ALC Output  5.0dBFS
1
0
0
ALC Output  6.0dBFS 6.0dBFS > ALC Output  8.5dBFS
1
0
1
ALC Output  6.0dBFS 6.0dBFS > ALC Output  7.2dBFS
1
1
0
ALC Output  8.5dBFS 8.5dBFS > ALC Output  12.0dBFS
1
1
1
ALC Output  8.5dBFS 8.5dBFS > ALC Output  10.1dBFS
Table 36. ALC Limiter ATT Step
Output
ATT Amount [dB]
+0.53dBFS ≤ Output Level (*)
0.38148
–1.16dBFS ≤ Output Level < +0.53dBFS
0.06812
LM-LEVEL ≤ Output Level < –1.16dBFS
0.02548
(*) Comparison with the next output data.
016001936-E-00
- 51 -
2016/03