ak4538 AKM Semiconductor, Inc., ak4538 Datasheet - Page 26

• Manufacturer Part Number: ak4538
• Description: 16bit ?? Codec With Mic/hp/spk-amp
• Manufacturer: AKM Semiconductor, Inc.

ASAHI KASEI
n MIC Gain Amplifier
AK4538 has a Gain Amplifier for Microphone input. This gain is 0dB or +20dB, selected by the MGAIN bit. The typical
input impedance is 30k .
n MIC Power
The MPI and MPE pins supply power for the Microphone. These output voltages are 0.75 x AVDD (typ) and the maximum
output current is 1.25mA. MPWRI/MPWRE bit can control output from MPI and MPE pin.
n MIC Detection Function
The AK4538 includes the detection function of microphone.
Example of the detection of external microphone.
(1) MPWRE= “1”.
(2) MPE drives external microphone.
(3) DTMIC bit is set by Table 17.
MS0198-E-01
Input Level of DTM
< 0.050 x AVDD
0.075 x AVDD
MGAIN bit
Table 17. Microphone detection result
Figure 20. Microphone Power Supply
0
1
MPE
MDT
Table 16. Input Gain
MPI
EXT
INT
DTMIC
1
0
Input Gain
- 26 -
“MPWRE” bit
“MPWRI” bit
+20dB
0dB
500k
External microphone
0.075 x AVDD
Default
Disconnect
Connect
“DTMIC” bit
[AK4538]
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