AK4640_05 Datasheet, PDF (38/78 Pages) Asahi Kasei Microsystems – 16-Bit ΔΣ CODEC with MIC/HP/SPK-AMP

ASAHI KASEI
[AK4640]
„ Speaker Output
The output signal from analog volume is converted into a mono signal [(L+R)/2] and this signal is input to the
Speaker-amp via the ALC2 circuit. This Speaker-amp is a mono output controlled by BTL and can output a maximum of
300mW@ALC2=OFF and 250mW@ALC2=ON at 8Ω load when HVDD = 3.3V. When BEEP input is used for DAC
output, maximum power becomes 400mW. Figure 28 and Figure 29 indicates connection examples for 400mW output.
ALC2
Po(max)
0
300mW
1
250mW Default
Table 22. SPK-Amp Maximum Output Power
Speaker blocks (MOUT2, ALC2 and Speaker-amp) can be powered up/down by controlling the PMSPK bit. When the
PMSPK bit is “0”, the MOUT2, SPP and SPN pins are placed in a Hi-Z state.
When the SPPS bit is “0”, the Speaker-amp enters power-save-mode. In this mode, the SPP pin is placed in a Hi-Z state
and the SPN pin goes to HVDD/2 voltage. And then the Speaker output gradually changes to the HVDD/2 voltage and
this mode can reduce click noise at power-up. When the AK4640 is powered down, click noise can be also reduced by
first entering power-save-mode.
PMSPK bit
SPPS bit
SPP pin
Hi-Z
Hi-Z
SPN pin _Hi-Z ^HVDD/2
HVDD/2
Hi-Z
>1ms
Figure 27. Power-up/Power-down Timing for Speaker-amp
[Connection Example for 400mW output]
1) Using BEEPM pin
AK4640
20k
± 30%
SPK-Amp
>0
SPP
MOUT2
0.047u _16k
45%AVDD
BEEPM
BPMSP
SPN
Figure 28. Connection example for 400mW output using BEEPM pin
MS0273-E-02
- 38 -
2005/04