AK4650 Datasheet, PDF (27/86 Pages) Asahi Kasei Microsystems – 16Bit ΔΣ CODEC with MIC/HP/SPK-AMP & TSC

[AK4650]
■ MIC Gain Amplifier
The AK4650 has a Gain Amplifier for Microphone input. The gain is 0dB or +20dB, selected by the MGAIN bit. The
typical input impedance is 30kΩ.
MGAIN bit
Input Gain
0
0dB
(default)
1
+20dB
Table 10. MIC Input Gain
■ MIC Power
The MPI and MPE pins supply power for the Microphone. These output voltages are 2.2V (typ) and load resistance is
2kΩ (min). MPWRI and MPWRE bits control output from MPI and MPE pins, respectively. When LNMP bit = “1”, MPE
pin becomes LIN pin.
PMMIC bit MPWRI bit
MPI pin
0
x
Hi-Z
(default)
1
0
Hi-Z
1
Output
Table 11. Internal Microphone Power Supply (x: Don’t care)
PMMIC bit MPWRE bit
MPE pin
0
x
Hi-Z
(default)
1
0
Hi-Z
1
Output
Table 12. External Microphone Power Supply (x: Don’t care)
■ MIC Detection Function
The AK4650 includes the detection function of microphone.
Example of the detection of external microphone.
(1) MPWRE bit = “1”.
(2) MPE drives external microphone.
(3) DTMIC bit is set by Table 13.
Input Level of MDT
DTMIC bit
External microphone
> 0.247V
1
Connect
< 0.165V
0
Disconnect
Table 13. Microphone detection result
When RNMD bit = “1”, MDT pin becomes RIN pin.
MS0502-E-01
- 27 -
2007/04