[AK4675]
(2) ALCA Recovery Operation
ALCA recovery operation waits for the WTMA2-0 bits to be set after completing ALCA limiter operation. If the input
signal does not exceed “ALCA recovery waiting counter reset level” during the wait time, ALCA recovery operation is
executed. The SPGA value is automatically incremented by RGAINA1-0 bits up to the set reference level (REFA5-0 bits)
with zero crossing detection which timeout period is set by ZTMA1-0 bits. Then the SPGA is set to the same value for
both channels. ALCA recovery operation is executed at a period set by WTMA2-0 bits. When zero cross is detected at
both channels during the wait period set by WTMA2-0 bits, ALCA recovery operation waits until WTMA2-0 period and
the next recovery operation is executed. The setting period of WTMA2-0 bits should be same as ZTMA1-0 bits or longer
period.
When RGAINA1-0 bits are set to “10”, ALCA recovery operation is not executed though ALCA limiter
operation is executed.
During the ALCA recovery operation, when the ALCA output level exceeds ALCA limiter detection level (LMTHA bit),
the ALCA limiter operation is done immediately.
When
“ALCA recovery waiting counter reset level ≤ ALCA Output Signal < ALCA limiter detection level (LMTHA1-0)”
during the ALCA recovery operation, the waiting timer of ALCA recovery operation is reset. When
“ALCA recovery waiting counter reset level > ALCA Output Signal”,
the waiting timer of ALCA recovery operation starts.
The ALCA operation corresponds to the impulse noise. When the impulse noise is input, the ALCA recovery operation
becomes faster than a normal recovery operation.
Recovery Waiting Timer
WTMA2
WTMA1
WTMA0
OSCN bit = “0”
OSCN bit = “1”
MSEL bit = “0”
typ.
max
MSEL bit = “1”
49152/MCKIA
98304/MCKIA
196608/MCKIA
393216/MCKIA
786432/MCKIA
1572864/MCKI (default)
A
0
0
0
0
1
1
0
0
1
1
0
0
0
1
0
1
0
1
16.4ms
32.8ms
65.6ms
131.2ms
262.4ms
524.8ms
26.3ms
51.5ms
105.0ms
210.0ms
419.9ms
839.7ms
32768/MCKIA
65536/MCKIA
131072/MCKIA
262144/MCKIA
524288/MCKIA
1048576/MCKIA
1
1
1
1
0
1
1049.6ms 1679.4ms 2097152/MCKIA
2099.2ms 3358.8ms 4194304/MCKIA
3145728/MCKI
A
6291456/MCKI
A
Table 85. ALCA Recovery Waiting Timer Period
RGAINA1 RGAINA0 GAIN STEP
0
0
1
1
0
1
0
1
1 step
2 step
0 step
0.5dB
1.0dB
0dB
(default)
Reserved
Table 86. ALCA Recovery GAIN Step
MS0963-E-00
2008/05
- 113 -
AKM [ ASAHI KASEI MICROSYSTEMS ]
