ak5701 AKM Semiconductor, Inc., ak5701 Datasheet - Page 35

• Manufacturer Part Number: ak5701
• Description: 16-bit ?? Stereo Adc With Pll & Mic-amp
• Manufacturer: AKM Semiconductor, Inc.

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The ALC (Automatic Level Control) is done by ALC block when ALC bit is “1”.
1. ALC Limiter Operation
During the ALC limiter operation, when either Lch or Rch exceeds the ALC limiter detection level
and IVR values (same value) are attenuated automatically by the amount defined by the ALC limiter ATT step
When ZELMN bit = “0” (zero cross detection is enabled), the IVL and IVR values are 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), IVL and IVR values are 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 attenuation operation is executed continuously until the input signal level becomes ALC limiter detection level
(Table
when the input signal level exceeds LMTH1-0 bits.
MS0404-E-02
ALC Operation
LMTH1
22) or less. After completing the attenuation operation, unless ALC bit is changed to “0”, the operation repeats
0
0
1
1
ZTM1
LMTH0
0
0
1
1
0
1
0
1
ZELMN
Table 22. ALC Limiter Detection Level / Recovery Counter Reset Level
0
1
ZTM0
ALC Limier Detection Level
0
1
0
1
ALC Output ≥ −2.5dBFS
ALC Output ≥ −4.1dBFS
ALC Output ≥ −6.0dBFS
ALC Output ≥ −8.5dBFS
LMAT1
Table 24. ALC Zero Crossing Timeout Period
x
0
0
1
1
1024/fs
128/fs
256/fs
512/fs
Table 23. ALC Limiter ATT Step
LMAT0
0
1
0
1
x
128ms
8kHz
16ms
32ms
64ms
- 35 -
Zero Crossing Timeout Period
ALC Recovery Waiting Counter Reset Level
(Table
−2.5dBFS > ALC Output ≥ −4.1dBFS
−4.1dBFS > ALC Output ≥ −6.0dBFS
−6.0dBFS > ALC Output ≥ −8.5dBFS
ALC Limiter ATT Step
−8.5dBFS > ALC Output ≥ −12dBFS
1 step
2 step
4 step
8 step
1step
24).
16kHz
16ms
32ms
64ms
8ms
0.375dB
0.375dB
0.750dB
1.500dB
3.000dB
44.1kHz
11.6ms
23.2ms
2.9ms
5.8ms
(default)
(default)
(Table
22), the IVL
(default)
(Table
[AK5701]
2007/08
23).