AK4648 Datasheet, PDF (46/119 Pages) Asahi Kasei Microsystems – Stereo CODEC with MIC/HP/SPK-AMP

[AK4648]
■ MIC Gain Amplifier
The AK4648 has a gain amplifier for microphone input. The gain of MIC-Amp is selected by the MGAIN1-0 bits (Table
22). The typical input impedance is 60kΩ(typ.) @ MGAIN1-0 bits = “00” or 30kΩ(typ )@ MGAIN1-0 bits = “01”, “10”
or “11”.
MGAIN1 bit
0
0
1
1
MGAIN0 bit Input Gain
0
0dB
1
+20dB
0
+26dB
1
+32dB
Table 22. Mic Input Gain
(default)
■ MIC Power
When PMMP bit = “1”, the MPWR pin supplies power for the microphone. This output voltage is typically 0.75 x AVDD
and the load resistance is minimum 0.5kΩ. In case of using two sets of stereo mic, the load resistance is minimum 2kΩ for
each channel. Capacitor must not be connected directly to MPWR pin (Figure 33).
PMMP bit
MPWR pin
0
Hi-Z
1
Output
Table 23. MIC Power
(default)
MIC Power
MPWR pin
LIN1 pin
RIN1 pin
LIN2 pin
RIN2 pin
Figure 33. MIC Block Circuit
Microphone
Microphone
Microphone
Microphone
MS0625-E-01
- 46 -
2007/06