Earphone Interface Design - Quectel M85 Hardware Design

SPK2P
Module
AGND
Figure 30: Speaker Interface Design with an Amplifier for AOUT2
Texas Instrument's TPA6205A1is recommended for a suitable differential audio amplifier. There are
plenty of excellent audio amplifiers in the market.
NOTE
3.
The value of C1 and C2 here depends on the input impedance of audio amplifier.

3.8.4. Earphone Interface Design

MIC2N
MIC2P
Module
SPK2P
AGND
M85_Hardware_Design
Differential layout
C1
C2
Differential layout
22uF
AGND
Figure 31: Earphone Interface Design
Confidential / Released
Close to Speaker
Amplifier 10pF
circuit 0603
10pF
0603
Close to Socket
GND GND
4.7uF
10p
33pF
F
0603
0603
68R
33pF
10pF
0603 0603
ESD
GND
GND GND
GSM/GPRS Module
M85 Hardware Design
GND
33pF
ESD
0603
33pF ESD
0603
GND
GND
ESD
3
4
2
1
Amphenol
9001-8905-
AGND 050
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