ak4648 AKM Semiconductor, Inc., ak4648 Datasheet - Page 46

• Manufacturer Part Number: ak4648
• Description: Stereo Codec With Mic/hp/spk-amp
• Manufacturer: AKM Semiconductor, Inc.

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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 60k Ω (typ.) @ MGAIN1-0 bits = “00” or 30k Ω (typ )@ MGAIN1-0 bits = “01”, “10”
or “11”.
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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 0.5k Ω . In case of using two sets of stereo mic, the load resistance is minimum 2k Ω for
each channel. Capacitor must not be connected directly to MPWR pin (Figure 33).
MS0625-E-01
MIC Gain Amplifier
MIC Power
MIC Power
MGAIN1 bit
0
0
1
1
PMMP bit
0
1
Figure 33. MIC Block Circuit
MGAIN0 bit
Table 22. Mic Input Gain
Table 23. MIC Power
MPWR pin
LIN1 pin
RIN1 pin
LIN2 pin
RIN2 pin
0
1
0
1
- 46 -
MPWR pin
Output
Hi-Z
Input Gain
+20dB
+26dB
+32dB
0dB
(default)
(default)
Microphone
Microphone
Microphone
Microphone
[AK4648]
2007/06