AK5700 Datasheet, PDF (33/61 Pages) Asahi Kasei Microsystems – 16-Bit ΔΣ Mono ADC with PLL & MIC-AMP

ASAHI KASEI
[AK5700]
MPWR pin
1k
AIN+ pin
AIN− pin
1k
AK5700
MIC-Amp
Figure 33. Connection Example for Full-differential Mic Input (MDIF1bit = “1”)
„ MIC Gain Amplifier
The AK5700 has a gain amplifier for microphone input. The gain of MIC-Amp is selected by the MGAIN1-0 bits (see
Table 20). The typical input impedance is 60kΩ(typ)@MGAIN1-0 bits = “00” or 30kΩ(typ)@MGAIN1-0 bits = “01” or
“10”.
„ MIC Power
MGAIN1 bit
0
0
1
1
MGAIN0 bit Input Gain
0
0dB
1
+15dB
0
+30dB
1
N/A
Table 20. Mic Input Gain
Default
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 1.0kΩ. In case of using two sets of mono mic, the load resistance is minimum 2.0kΩ
for each channel. No capacitor must not be connected directly to MPWR pin (see Figure 34).
PMMP bit
MPWR pin
0
Hi-Z
1
Output
Table 21. MIC Power
Default
MIC Power
MPWR pin
MS0569-E-01
AIN1 pin
Microphone
AIN2 pin
Microphone
Figure 34. MIC Block Circuit
- 33 -
2006/12