ASAHI KASEI
[AK5355]
MIC Device Connection Example
Figure 9 and Figure 10 show the connection example of MIC Device. In this case, a mono microphone is connected to
LIN pin the AK5355. Unused RIN pin can be open. The power supply for the microphone is provided via 4.4kΩ (2.2kΩ
+ 2.2kΩ) from analog power supply. The power supply noise provided to the microphone should be care because the
microphone gain is usually high, around 40dB. In Figure 9, 1st order LPF by 2.2kΩ and 10µF is inserted between the
power supply and the microphone.
The AK5355 has a gain of +15dB in analog stage. However, as the usual application needs a gain of around 40dB or
50dB, the shortage of gain, 25dB or 35dB, should be covered by digital processing like DSP.
The total S/N in each gain level is shown in Table 3
Analog Gain
+15dB
Digital Gain
S/N
0dB
+25dB
+35dB
83dB
58dB
48dB
+15dB
+15dB
Table 3. S/N of each gain level
+
2.2µ
0.1µ
0.1µ
MIC
2.2k
2.2k
1
2
3
4
5
6
7
8
VCOM
RIN
LIN
TST1 16
NC 15
+
10µ
Mode
Setting
14
13
DIF
VSS
VA
PDN
Reset
Top View
Analog Supply
0.1µ
10µ
+
BCLK 12
MCLK 11
LRCK 10
2.1 ∼ 3.6V
Digital Supply
2.1 ∼ 3.6V
VD
+
Controller
10µ
0.1µ
SEL
NC
SDTO
9
Analog Ground
System Ground
Figure 9. MIC Device Connection Example (AK5355VT)
MS0113-E-01
2005/01
- 14 -
AKM [ ASAHI KASEI MICROSYSTEMS ]
