AK4635 Datasheet, PDF (38/81 Pages) Asahi Kasei Microsystems – 16-Bit Mono CODEC with ALC & MIC/SPK/Video-AMP

[AK4635]
MPI pin
1k
MICP pin
MICNpin
1k
MIC-Power
AK4635
MIC-Amp
A/D HPF
Audio
I/F
BICK pin
FCK pin
STDO pin
Figure 37. MIC Differential Input Circuit
■ MIC Gain Amplifier
The AK4635 has a Gain Amplifier for Microphone input. These gains are selected by the MGAIN3-0 bit. The typical
input impedance is 30kΩ.
MGAIN3 bit
0
0
0
0
0
0
0
0
1
1
MGAIN2 bit MGAIN1 bit MGAIN0 bit
0
0
0
0
0
1
0
1
0
0
1
1
1
0
0
1
0
1
1
1
0
1
1
1
0
0
0
0
0
1
Others
Table 20. Input Gain
Input Gain
0dB
+20dB
+26dB
+32dB
+10dB
+17dB
+23dB
+29dB
+3dB
+6dB
N/A
(default)
■ MIC Power
The MPI pin supplies power for the Microphone. This output voltage is proportional to 0.8 x AVDD typically and the
load resistance is minimum 2kΩ. No capacitor must not be connected to the MPI pin, directly. (Figure 38)
MPI pin
≥ 2k
MIC pin
MIC-Power
AK4635
MIC-Amp
A/D HPF
Audio
I/F
BICK pin
FCK pin
STDO pin
Figure 38. MIC Block Circuit
Rev. 0.6
- 38 -
2007/10