[AK4646]
■ MIC Gain Amplifier
The AK4646 has a gain amplifier for microphone input. The gain of MIC-Amp is selected by the MGAIN2-0 bits (Table
19). The typical input impedance is 30kΩ (typ).
MGAIN2 bit MGAIN1 bit MGAIN0 bit
Input Gain
0dB
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
+20dB
+26dB
+32dB
+10dB
+17dB
+23dB
+29dB
(default)
Table 19. Mic Input Gain
■ MIC Power
When PMMP bit = “1”, the MPWR pin supplies power for the microphone. This output voltage is typically 0.8 x AVDD
and the load resistance is minimum 0.5kΩ. In case of using two sets of stereo microphone, the load resistance is minimum
2kΩ for each channel. Any capacitor must not be connected directly to MPWR pin (Figure 23).
PMMP bit
MPWR pin
Hi-Z
Output
0
1
(default)
Table 20. MIC Power
MIC Power
MPWR pin
Microphone
Microphone
Microphone
Microphone
LIN1 pin
RIN1 pin
LIN2 pin
RIN2 pin
Figure 23. MIC Block Circuit
MS0557-E-05
2011/01
- 31 -
AKM [ ASAHI KASEI MICROSYSTEMS ]
