AK4671_10 Datasheet, PDF (60/166 Pages) Asahi Kasei Microsystems – Stereo CODEC with MIC/RCV/HP-AMP

[AK4671]
■ MIC Detection
The AK4671 has the detecting function of microphone. The external circuit is showed in Figure 56.
The followings show the example of external microphone detection sequence:
(1) PMMP bit should be set to “1” after CPU detects the jack insertion of microphone or headphone.
(2) The MPWR pin drives external microphone.
(3) The GPO2 pin (at GPOM2 bit = “1”) and DTMIC bit are set as Table 21. In case of Headset (with Mic), the input
voltage of MDT pin is higher than 0.075 x AVDD because of the relationship between the bias resistance at the
MPWR pin (typ. 2.2kΩ) and the microphone impedance. In case of Headphone (No Mic), the input voltage of MDT
pin is 0V because the pin of headphone jack connected to the MDT pin is assigned as ground.
Input Level of MDT pin
≥ 0.075 x AVDD
< 0.050 x AVDD
GPO2 pin
DTMIC bit
H
1
L
0
Table 21. Microphone Detection Result
Result
Mic (Headset)
No Mic (Headphone)
MPWR ^{PMMP bit}
AK4671
Headset
Headphone
GMR L
or
G
RL
LIN1
LIN2
MDT
typ.
500k
DTMIC bit
0.075 x AVDD
Figure 56. Microphone Power Supply and Mic Detection
MS0666-E-02
- 60 -
2010/06