AK4634EN Datasheet, PDF (38/94 Pages) Asahi Kasei Microsystems – 16-Bit Mono CODEC with ALC & MIC/SPK -AMP

[AK4634]
MPI pin
1k
MICP pin
MICNpin
1k
MIC-Power
mp
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 30k.
MGAIN3 bit
0
0
0
0
0
0
0
0
1
1
MGAIN2 bit MGAIN1 bit MGAIN0 bit Input Gain
0
0
0
0dB
0
0
1
+20dB
0
1
0
+26dB
0
1
1
+32dB
1
0
0
+10dB
1
0
1
+17dB
1
1
0
+23dB
1
1
1
+29dB
0
0
0
+3dB
0
0
1
+6dB
Others
N/A
Table 20. Input Gain (N/A: Not available)
(default)
■ MIC Power
The MPI pin supplies power for a Microphone. This output voltage is proportional to 0.8 x AVDD typically and the load
resistance is minimum 2k. Any capacitor must not be connected to the MPI pin directly. (Figure 34)
MPI pin
 2k
MIC pin
MIC-Power
mp
AK4634
MIC-Amp
A/D HPF
Audio
I/F
BICK pin
FCK pin
STDO pin
Figure 34. MIC Block Circuit
MS0686-E-03
- 38 -
2014/10