AK5355 Datasheet, PDF (11/14 Pages) Asahi Kasei Microsystems – LOW POWER 16BIT ADC

ASAHI KASEI
[AK5355]
„ MIC Device Connection Example
Figure 8 shows 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 8, 1^st 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
Digital Gain
S/N
+15dB
0dB
83dB
+15dB
+25dB
58dB
+15dB
+35dB
48dB
Table 3. S/N of each gain level
0.1µ
MIC
+
2.2µ
0.1µ
2.2k
2.2k
Analog Supply
2.1 ∼ 3.6V
Digital Supply
2.1 ∼ 3.6V
+
10µ
1 VCOM
2 RIN
TST1 16
NC 15
3 LIN
DIF 14
10µ ₊
4 VSS
0.1µ
5 VA
Top View ^{PDN 13}
BCLK 12
10µ ⁺ 0.1µ
6 VD
7 SEL
MCLK 11
LRCK 10
8 NC
SDTO 9
Mode
Setting
Reset
Controller
Analog Ground
System Ground
Figure 8. MIC Device Connection Example
MS0113-E-00
- 11 -
2001/08