u-blox SARA-G3 Series System Integration Manual page 127

 Connect the other pin of the mechanical switch integrated in the two SIM connectors (e.g. the SW1
pins as described in Figure 46Figure
of a strong (e.g. 1 k) pull-up resistor, as the R1 and R3 resistors in
 Provide a weak (e.g. 470 k) pull-down resistor at the SIM detection line, between the double-
throw digital switch and the related SIM connector as the R2 and R4 resistors in
 Provide a 100 nF bypass capacitor (e.g. Murata GRM155R71C104K) at the SIM supply line
(VSIM), close to the relevant pad of the two SIM connectors, to prevent digital noise
 Provide a bypass capacitor of about 22 pF to 47 pF (e.g. Murata GRM1555C1H470J) on each SIM
line (VSIM, SIM_CLK, SIM_IO, SIM_RST), very close to each relevant pad of the two SIM
connectors, to prevent RF coupling especially in case the RF antenna is placed closer than 10 - 30
cm from the SIM card holders
 Provide a very low capacitance (i.e. less than 10 pF) ESD protection (e.g. Tyco Electronics
PESD0402-140) on each externally accessible SIM line, close to each relevant pad of the two SIM
connectors, according to the EMC/ESD requirements of the custom application
 Limit capacitance and series resistance on each SIM signal (SIM_CLK, SIM_IO, SIM_RST) to match
the requirements for the SIM interface (27.7 ns is the maximum allowed rise time on the SIM_CLK
line, 1.0 µs is the maximum allowed rise time on the SIM_IO and SIM_RST lines)
SARA-G3 series
TP
V_INT 4
SPDT
Digital
Switch
VCC
SIM _DET 42 Y
S
GND
U2
3V8
4PDT
Analog
Switch
VCC
1VSIM
VSIM 41 VSIM
2VSIM
1DAT
SIM _IO 39 DAT
2DAT
1CLK
SIM _CLK
38 CLK
2CLK
1RST
SIM _RST RST
40
2RST
SEL
GND
U1
Application
Processor
GPIO
R5
Figure 46: Application circuit for the connection to two removable SIM cards, with SIM detection implemented
UBX-13000995 - R06
46) to the V_INT 1.8 V supply output of the module by means
C12
I0
I1
C1 C2 C3 C4 C5
C11
C6 C7 C8 C9 C10
Objective Specification
SARA-G3 series - System Integration Manual
Figure 46Figure 46
Figure 46Figure 46
FIRST
SIM CARD
HOLDER
SW1
R1
SW2
R2
VPP (C6)
VCC (C1)
IO (C7)
CLK (C3)
RST (C2)
GND (C5)
D1 D2 D3 D4 D5 D6
J1
SECOND
SIM CARD
HOLDER
SW1
R3
SW2
R4
VPP (C6)
VCC (C1)
IO (C7)
CLK (C3)
RST (C2)
GND (C5)
D7 D8 D9 D10 D11 D12
J2
Design-in
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