AK4665A Datasheet, PDF (16/52 Pages) Asahi Kasei Microsystems – 20-Bit Stereo CODEC with MIC/HP-AMP

ASAHI KASEI
[AK4665A]
„ Digital High Pass Filter
The AK4665A has a Digital High Pass Filter (HPF) to cancel DC-offsets in ADC. The cut-off frequency of the HPF is
3.4Hz at fs=44.1kHz. This filter scales with the sampling frequency (fs).
„ Mono-MIC Gain Amplifier (MICIN pin)
The AK4665A has a gain amplifier for mono-mic input. The gain of Mic-Amp is selected by MGAIN1-0 bits (see Table
5). The input impedance is 60kΩ(typ) at MGAIN1-0 bits = “00”, “01” and 30kΩ(typ) at MGAIN1-0 bits = “10”, “11”.
MGAIN1 bit
0
0
1
1
MGAIN0 bit Input Gain Input Resistance
0
0dB
60kΩ (typ)
1
−6dB
60kΩ (typ)
0
+6dB
30kΩ (typ)
1
+30dB
30kΩ (typ)
Table 5. MIC Input Gain
Default
„ MIC Power (MPWR pin)
When PMMP bit is “1”, MPWR pin supplies power for the microphone. This output voltage is 2.0V(typ), and the load
resistance is minimum 2kΩ. Capacitor must not be connected directly to MPWR pin (see Figure 12).
PMMP bit
MPWR pin
0
Hi-Z
1
Output
Table 6. MIC Power
Default
MIC Power
MPWR
≥ 2kΩ
MIC-Amp
MICIN
Microphone
Figure 12. MIC Block Circuit
MS0440-E-01
- 16 -
2006/05