ak4644 AKM Semiconductor, Inc., ak4644 Datasheet - Page 38

• Manufacturer Part Number: ak4644
• Description: Stereo Codec With Mic/hp/rcv-amp
• Manufacturer: AKM Semiconductor, Inc.

ASAHI KASEI
The AK4644 has a gain amplifier for microphone input. The gain of MIC-Amp is selected by the MGAIN1-0 bits (see
Table 23). The typical input impedance is 60kΩ(typ)@MGAIN1-0 bits = “00” or 30kΩ(typ)@MGAIN1-0 bits = “01”,
“10” or “11”.
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. No capacitor must not be connected directly to MPWR pin (see Figure 34).
MS0477-E-01
MIC Gain Amplifier
MIC Power
MIC Power
MGAIN1 bit
0
0
1
1
PMMP bit
0
1
Figure 34. MIC Block Circuit
MGAIN0 bit
Table 23. Mic Input Gain
Table 24. MIC Power
MPWR pin
LIN1 pin
RIN1 pin
LIN2 pin
RIN2 pin
0
1
0
1
- 38 -
MPWR pin
Output
Hi-Z
Input Gain
+20dB
+26dB
+32dB
0dB
Default
Default
Microphone
Microphone
Microphone
Microphone
[AK4644]
2006/10