SARA-G3 series - System Integration Manual
UBX-13000995 - R06 Objective Specification Design-in
Page 144 of 218
the 8 or 4 loudspeaker. (See the Analog Devices SSM2305CPZ filter-less mono 2.8 W class-D
Audio Amplifier in the circuit described in Figure 58Figure 58.)
Provide proper parts on each line connected to the external loudspeaker as noise and EMI
improvments, 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 loudspeaker
line to solid ground plane (C6 and C7 capacitors in Figure 58Figure 58).
Provide additional ESD protection (e.g. EPCOS CA05P4S14THSG varistor array) if the analog audio
lines will be externally accessible on the application device, according to EMC/ESD requirements of the
custom application. The protection should be mounted close to an accessible point of the line (D1
and D2 parts in the circuit described in Figure 58Figure 58).
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
D2
D1
C6 C7
L2
L1
C5C4
LSPK
Loud-Speaker
Connector
J2
Microphone
Connector
MIC
J1
OUT+
IN+
GND
U1
OUT-
IN-
C8
C9
R5
R6
VDD
C11C10
Audio
Amplifier
VCC
Figure 58: Analog audio interface hands-free mode application circuit
Part Number – Manufacturer
10 µF Capacitor Ceramic X5R 0603 20% 6.3 V
GRM188R60J106ME47 – Murata
100 nF Capacitor Ceramic X7R 0402 10% 16 V
GRM155R71C104KA88 – Murata
27 pF Capacitor Ceramic C0G 0402 5% 25 V
GRM1555C1H270JA01 – Murata
47 nF Capacitor Ceramic X7R 0402 10% 16V
GRM155R71C473KA01 – Murata
Low Capacitance ESD Protection
USB0002RP or USB0002DP – AVX
82 nH Multilayer inductor 0402
(self resonance frequency ~1 GHz)
2.2 kΩ Electret Microphone
2.2 kΩ Resistor 0402 5% 0.1 W
RC0402JR-072K2L – Yageo Phycomp
Formatted: English (U.S.)
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