Datasheet

[AK4646]

MS0557-E-06 2011/06

- 31 -

■ MIC Gain Amplifier

The AK4646 has a gain amplifier for microphone input. The gain of MIC-Amp is selected by the MGAIN2-0 bits (

Table

19). The typical input impedance is 30k

Ω (typ).

MGAIN2 bit MGAIN1 bit MGAIN0 bit Input Gain

0 0 0 0dB

0 0 1 +20dB (default)

0 1 0 +26dB

0 1 1 +32dB

1 0 0 +10dB

1 0 1 +17dB

1 1 0 +23dB

1 1 1 +29dB

Table 19. Mic Input Gain

■ MIC Power

When PMMP bit = “1”, the MPWR pin supplies power for the microphone. This output voltage is typically 0.8 x AVDD

and the load resistance is minimum 0.5k

Ω. In case of using two sets of stereo microphone, the load resistance is minimum

Ω for each channel. Any capacitor must not be connected directly to MPWR pin (Figure 23).

PMMP bit MPWR pin

0 Hi-Z (default)

1 Output

Table 20. MIC Power

MPWR pin

≥

MIC Power

Microphone

LIN1 pin

Microphone

RIN1 pin

Microphone

LIN2 pin

Microphone

RIN2 pin

≥

Figure 23. MIC Block Circuit