AK4634 Datasheet, PDF (36/77 Pages) Asahi Kasei Microsystems – 16-Bit Mono CODEC with ALC & MIC/SPK-AMP

[AK4634]
MPI pin
1k
MICP pin
MICNpin
1k
MIC-Power
AK4634
MIC-Amp
A/D HPF
Audio
I/F
Figure 33. MIC Differential Input Circuit
BICK pin
FCK pin
STDO pin
■ MIC Gain Amplifier
The AK4634 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. Any capacitor must not be connected to the MPI pin, directly. (Figure 34)
MPI pin
≥ 2k
MIC pin
MIC-Power
AK4634
MIC-Amp
A/D HPF
Audio
I/F
BICK pin
FCK pin
STDO pin
Figure 34. MIC Block Circuit
Rev. 0.5
- 36 -
2007/10