AK5701_07 Datasheet, PDF (34/64 Pages) Asahi Kasei Microsystems – 16-Bit ΔΣ Stereo ADC with PLL & MIC-AMP

[AK5701]
MPWR pin
1k
IN1− pin
IN1+ pin
1k
AK5701
MIC-Amp
Figure 37. Connection Example for Full-differential Mic Input (MDIF1/2 bits = “1”)
■ MIC Gain Amplifier
The AK5701 has a gain amplifier for microphone input. The gain of MIC-Amp is selected by the MGAIN1-0 bits (Table
20). The typical input impedance is 60kΩ(typ)@MGAIN1-0 bits = “00” or 30kΩ(typ)@MGAIN1-0 bits = “01” or “10”.
MGAIN1 bit MGAIN0 bit Input Gain
0
0
0dB
0
1
+15dB
(default)
1
0
+30dB
1
1
N/A
Table 20. Mic Input Gain (N/A: Not available)
■ 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. Any capacitor must not be connected directly to the MPWR pin (Figure 38).
PMMP bit
MPWR pin
0
Hi-Z
1
Output
Table 21. MIC Power
(default)
MIC Power
MPWR pin
LIN1 pin
RIN1 pin
LIN2 pin
RIN2 pin
Figure 38. MIC Block Circuit
Microphone
Microphone
Microphone
Microphone
MS0404-E-02
- 34 -
2007/08