AK7755EN_16 Datasheet, PDF (92/109 Pages) Asahi Kasei Microsystems – DSP with Mono ADC Stereo CODEC + Mic/Lineout Amp

[AK7755]
■ Analog Output Block
The AK7755 can output an analog mixing signal of DAC and line-in amplifier outputs from the OUT3
pin. AD conversion is available by setting PMAD2L bit (CONT0E: D5) to “1” even when the analog
mixing output is ON.
LIN pin
AK7755
LIGN[3:0]
Mono
ADC
Stereo
DAC Lch
Stereo
DAC Rch
LOVOL1[3:0]
LO3SW1(SW1)
LOVOL2[3:0]
LO3SW2(SW2) M
I
LO3SW3(SW3) ^X
LOVOL3[3:0]
OUT1 pin
OUT2 pin
OUT3 pin
Figure 74. Analog Output Circuit
1. Line Output Amplifier
The AK7755 has a line output amplifier. The maximum amplitude is 0.76 × AVDD (2.51[Vpp]
@AVDD=3.3V) and load resistance is 10k (min). LOVOL1/2/3[3:0] bits (CONT14: D3-D0/
CONT14: D7-D4/ CONT13: D3-D0) control the stereo line output volume. A pop noise occurs if the
output gain is changed during operation.
LOVOL1,L2,L3[3:0]
0h
1h
2h
3h
4h
5h
6h
7h
Attenuation LOVOL1, L2, L3[3:0]
Mute(default)
8h
-28dB
9h
-26dB
Ah
-24dB
Bh
-22dB
Ch
-20dB
Dh
-18dB
Eh
-16dB
Fh
Table 11. Line Output Volume
Attenuation
-14dB
-12dB
-10dB
-8dB
-6dB
-4dB
-2dB
0dB
2. Output1 and Output2
The OUT1 and OUT2 pins are connected to the L and R channels of the internal stereo DAC,
respectively. The relationship of each control bit and the OUT1 and OUT2 pins are shown below.
The OUT1 and OUT2 pins output settings are controlled by PMLO1/2 bit (CONT0E: D2/D3),
PMDAL/R bit (CONT0E: D0 /D1) and LOVOL1/2[3:0] bits (CONT014: D3-D0/D7-D4).
PMLO1 bit
0
1
1
1
PMDAL bit
X
0
1
1
LOVOL1[3:0] bits
X
X
0h(mute)
1h-Fh
OUT1 pin Output
Hi-Z
1/2 x AVDD
1/2 x AVDD
DAC Lch Output
PMLO2 bit
0
1
1
1
PMDAR bit
X
0
1
1
LOVOL2[3:0] bits
X
X
0h(mute)
1h-Fh
OUT2 pin Output
Hi-Z
1/2 x AVDD
1/2 x AVDD
DAC Rch Output
014006643-E-00
- 92 -
2014/10