Reference Circuit Design For Headset Interface; Reference Circuit Design For Loudspeaker Interface; Design Considerations For Audio Interfaces - Quectel SC200R Series Hardware Design

3.22.3. Reference Circuit Design for Headset Interface

MIC_GND
MIC2_P
HPH_L
HS_DET
HPH_R
HPH_REF
Module
Figure 26: Reference Circuit Design for Headphone Interface

3.22.4. Reference Circuit Design for Loudspeaker Interface

SPK_P EARP
EA
SPK_N
RN
Module
Figure 27: Reference Circuit Design for Loudspeaker Interface

3.22.5. Design Considerations for Audio Interfaces

It is recommended to use the electret microphone with dual built-in capacitors (e.g. 10 pF and 33 pF) to
filter out RF interference, thus reducing TDD noise. The 33 pF capacitor is applied to filter out RF
interference when the module is transmitting at EGSM900. Without this capacitor, TDD noise could be
heard during voice calls. The 10 pF capacitor is used to filter out RF interference at DCS1800. Please
note that the resonant frequency point of a capacitor largely depends on its material and manufacturing
SC200R&SC262R_Series_Hardware_Design
R1
0R
F1
R2
20K
C3
C4 C5
33 pF 33 pF 33 pF
C1 C2
33 pF
33 pF
F2
F3
F4
D1 D2 D3 D4
ESD
F1
F2
D1
Smart Module Series
1
5
4
3
6
2
R3
0R
D2
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