AK7755EN_16 Datasheet, PDF (93/109 Pages) Asahi Kasei Microsystems – DSP with Mono ADC Stereo CODEC + Mic/Lineout Amp

[AK7755]
3. OUT3 (Analog Mixer）
The AK7755 can output an analog mixing signal of DAC and line-in amplifier outputs from the OUT3
pin by setting LO3SW1 bit (CONT09: D1), LO3SW2 bit (CONT09: D2) and LO3SW3 bit (CONT09:
D3).
The line-out amplifier is powered up by setting PMLO3 bit = “1”. Each switch is disconnected and the
OUT3 pin outputs 1/2 × AVDD when LOVOL3[3:0] bits (CONT13: D3-D0) = 0h. L and R channel
signals of the DAC are input to the mixer by setting LO3SW1 bit and LO3SW2 bit to “1” while the
setting of LOVOL3[3:0] bits is not 0h. L and R channel signals of the DAC are not gained by the mixer
block.
The output signal of line-in amplifier is input to the mixer by setting LO3SW3 bit to “1” while the
setting of LOVOL3[3:0] bits is not 0h. Adjust the input voltage and line-in amplifier gain (LIGN[3:0]
bits (CONT13: D7-D4)) to prevent the mixing output exceeds 0.67 × AVDD[Vpp] since the line-in
amplifier output is gained +18dB by the mixer block.
The maximum amplitude of the line-out output is 0.76 × AVDD[Vpp]. VOLDAL[7:0] bits (CONT18:
D7-D0), VOLDAR[7:0] bits (CONT19: D7-D0), LIGN[3:0] bits and LOVOL3[3:0] bits should be
adjusted to not exceed this maximum level.
PMLO3
0
1
1
1
1
1
1
1
1
1
LOVOL3[3:0]
X
0h(mute)
1h-Fh
1h-Fh
1h-Fh
1h-Fh
1h-Fh
1h-Fh
1h-Fh
1h-Fh
LO3SW1
X
X
0
0
0
0
1
1
1
1
LO3SW2
X
X
0
0
1
1
0
0
1
1
LO3SW3
X
X
0
1
0
1
0
1
0
1
SW1
OFF
OFF
OFF
OFF
OFF
OFF
ON
ON
ON
ON
SW2
OFF
OFF
OFF
OFF
ON
ON
OFF
OFF
ON
ON
SW3
OFF
OFF
OFF
ON
OFF
ON
OFF
ON
OFF
ON
Table 12. OUT3 pin Output Switching Setting
014006643-E-00
- 93 -
2014/10