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AK4564 Datasheet, PDF (24/48 Pages) Asahi Kasei Microsystems – 16BIT CODEC WITH BUILT-IN ALC AND MIC/HP/SPK-AMP | |||
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ASAHI KASEI
[AK4564]
n SPEAKER BLOCK
The output signal from DAC is converted into a mono signal, [(L+R)/2], and is supplied to Speaker-Amp via ALC2
circuit. This Speaker-Amp has a monaural output by BTL, which can be output up to 80mW at 8â¦. Speaker Blocks
(MOUT, ALC2 and Speaker-Amp) can be powered-up/down by SPKP bit. When SPKP bit is â0â, MOUT, SP0 and SP1
pins go Hi-Z. When SPPS bit is â0â and SPKP bit is â1â, Speaker-Amp becomes Power-Save-Mode. Then SP0 pin goes
Hi-Z and SP1 pin is output to SVDD/2 via 100k ⦠(typ.).
When PDN pin changes from âLâ to âHâ after power-up, Speaker-Amp goes to Power-Save-Mode. In Power-Save-Mode,
SP1 pin gradually become HVCM voltage via an internal resistor (typ.200kâ¦) from Hi-Z to decrease a pop noise. When
Power-down (SPKP = â0â), the pop noise can be decreased by controlling via Power-Save-Mode.
* When Headphone-Amp and Speaker-Amp are powered-up at the same time, refer to the condition of
âNote 7â, âNote 8â and âNote 10â.
1. Mono Output
MOUT pin outputs analog mixed signal, [(L+R)/2] of DAC output. When MOUT bit is â0â, this output is disabled and
MOUT pin goes to VCOM voltage. The load impedance is 10k⦠(min.). When SPKP bit is â0â, MOUT pin becomes
Power-Down-Mode and outputs Hi-Z.
2. ALC2
The input resistance of ALC2 is 23k⦠(typ.) and centered around VCOM voltage. The level diagram of ALC2
operation is shown in Figure 19
ALC2 limiter detection level is â6.5dBV regardless of power supply voltage. When the input signal level exceeds
â6.5dBV (=FS-2dB@AVDD=2.8V), the output level of ALC2 is limited.
When the signal over â6.5dBV and is input continuously to the ALC2 circuit, the changing period of ALC2 limiter
operation is 2/fs=42µs@fs=48kHz and the output level is attenuated by 0.5dB/step. The ALC2 recovery operation is
done by zero crossing detection and the output is gained by 1dB/step. The ALC2 recovery operation is done until the
output level of Speaker-Amp goes to â8.5dBV(=FS-4dB@AVDD=2.8V). The ALC2 recovery operation period is fixed
to 2048/fs=42.7mS@fs=48kHz. When inputting signal between â6.5dBV and â8.5dBV, both the limiter and recovery
operations of ALC2 are not done.
When PDN pin changes from âLâ to âHâ or SPKP bit changes from â0â to â1â, the initilizing cycle (2048/fs = 42.7ms
@fs=48kHz) starts. ALC2 is disabled during initilizing cycle, ALC2 starts after finishing the initilizing cycle.
Parameter
Operation Start Level
Period
fs=48kHz
fs=32kHz
Zero Crossing Detection
ATT/GAIN
ALC2 Limiter operation
-6.5dBV
2/fs = 42µs
2/fs = 63µs
No
0.5dB step
Table 4. Content of ALC2
ALC2 Recovery operation
-8.5dBV
2048/fs = 42.7ms
2048/fs = 64ms
Yes(Timeout = 2048/fs )
1dB step
MS0140-E-01
- 24 -
2002/07
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