AK4343EN AKM [Asahi Kasei Microsystems], AK4343EN Datasheet - Page 40

• Manufacturer Part Number: AK4343EN
• Description: Stereo DAC with HP/RCV/SPK-AMP
• Manufacturer: AKM [Asahi Kasei Microsystems]

ASAHI KASEI
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 (Table 24), the AVL
and AVR values (same value) are attenuated automatically by the amount defined by the ALC limiter ATT step (Table
25).
When ZELMN bit = “0” (zero cross detection is enabled), the AVL and AVR 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 (Table 26).
When ZELMN bit = “1” (zero cross detection is disabled), AVL and AVR values are immediately (period: 1/fs) changed
by ALC limiter operation. Attenuation step is fixed to 1 step regardless as the setting of LMAT1-0 bits.
The attenuation operation is done continuously until the input signal level becomes ALC limiter detection level (Table 24)
or less. After completing the attenuation operation, unless ALC bit is changed to “0”, the operation repeats when the input
signal level exceeds LMTH1-0 bits.
MS0478-E-01
ALC Operation
LMTH1
0
0
1
1
ZTM1
LMTH0
0
0
1
1
0
1
0
1
ZELMN
Table 24. 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 25. ALC Limiter ATT Step (x: Don’t care)
Table 26. ALC Zero Crossing Timeout Period
0
0
1
1
x
1024/fs
128/fs
256/fs
512/fs
LMAT0
0
1
0
1
x
128ms
8kHz
16ms
32ms
64ms
- 40 -
Zero Crossing Timeout Period
ALC Recovery Waiting Counter Reset Level
−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
16kHz
16ms
32ms
64ms
8ms
0.375dB
0.750dB
1.500dB
3.000dB
0.375dB
44.1kHz
11.6ms
23.2ms
2.9ms
5.8ms
Default
Default
Default
[AK4343]
2006/10