Ublox SARA-G300, System Integration Manual

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SARA-G3 and SARA-U2 series - System Integration Manual
UBX-13000995 - R26 Design-in
Page 150 of 217

Provide proper parts on each line connected to the receiver / speaker as noise and EMI improvements, to
minimize RF coupling, according to EMC requirements of the custom application.
o
Mount a 27 pF bypass capacitor (e.g. Murata GRM1555C1H270J) from each speaker line to solid
ground plane (C6 and C7 capacitors in Figure 83).

Provide additional ESD protection (e.g. Bourns CG0402MLE-18G varistor) if the analog audio lines will be
externally accessible on the application device, according to the EMC/ESD requirements of the custom
application. Mount the protection close to an accessible point of the line (D1-D4 in Figure 83).
SARA-G340
SARA-G350
49
MIC_P
R1
R2 R4
44
SPK_P
48
MIC_N
45
SPK_N
R3
C1
46
MIC_BIAS
47
MIC_GND
C2
C3
D3
D1
C6 C7
L2
L1
C5 C4
SPK Speaker
Connector
J2
Microphone
Connector
MIC
J1
D4
D2
Figure 83: Analog audio interface headset and handset mode application circuit
Reference Description Part Number – Manufacturer
C1 10 µF Capacitor Ceramic X5R 0603 20% 6.3 V GRM188R60J106ME47 – Murata
C2, C3 100 nF Capacitor Ceramic X7R 0402 10% 16 V GRM155R71C104KA88 – Murata
C4, C5, C6, C7 27 pF Capacitor Ceramic C0G 0402 5% 25 V GRM1555C1H270JA01 – Murata
D1, D2, D3, D4 Low Capacitance ESD Protection CG0402MLE-18G - Bourns
J1 Microphone Connector Various Manufacturers
J2 Speaker Connector Various Manufacturers
L1, L2 82 nH Multilayer inductor 0402
(self resonance frequency ~1 GHz) LQG15HS82NJ02 – Murata
MIC 2.2 k Ω Electret Microphone Various Manufacturers
R1, R2, R3, R4 2.2 k Ω Resistor 0402 5% 0.1 W RC0402JR-072K2L – Yageo Phycomp
SPK 16 Ω Speaker Various Manufacturers
Table 54: Example of components for analog audio interface headset and handset mode application circuit
If the analog audio interface is not used, the analog audio pins ( MIC_BIAS , MIC_GND , MIC_P , MIC_N ,
SPK_P
,
SPK_N
) can be left unconnected on the application board.