u-blox LARA-R203 System Integration Manual page 102

LARA-R2 series
VSIM
41
SIM_IO 39
SIM_CLK
38
SIM_RST
40
Application
Processor
GPIO
Figure 49: Application circuit for the connection to two removable SIM cards, with SIM detection not implemented
Reference Description
C1 – C4, C6 – C9 33 pF Capacitor Ceramic C0G 0402 5% 25 V
C5, C10, C11 100 nF Capacitor Ceramic X7R 0402 10% 16 V
D1 – D8 Very Low Capacitance ESD Protection
R1 47 kΩ Resistor 0402 5% 0.1 W
J1, J2 SIM Card Holder
6 positions, without card presence switch
U1 4PDT Analog Switch,
with Low On-Capacitance and Low On-Resistance
Table 39: Example of components for the connection to two removable SIM cards, with SIM detection not implemented
2.5.1.2 Guidelines for SIM layout design
The layout of the SIM card interface lines (VSIM, SIM_CLK, SIM_IO, SIM_RST) may be critical if the SIM card is
placed far away from the LARA-R2 series modules or in close proximity to the RF antenna: these two cases should
be avoided or at least mitigated as described below.
In the first case, the long connection can cause the radiation of some harmonics of the digital data frequency as
any other digital interface: keep the traces short and avoid coupling with RF line or sensitive analog inputs.
In the second case, the same harmonics can be picked up and create self-interference that can reduce the sensitivity
of cellular receiver channels whose carrier frequency is coincidental with harmonic frequencies: placing the RF
bypass capacitors suggested in Figure 48 near the SIM connector will mitigate the problem.
In addition, since the SIM card is typically accessed by the end user, it can be subjected to ESD discharges: add
adequate ESD protection as suggested in Figure 48 to protect the module SIM pins near the SIM connector.
Limit the capacitance and series resistance on each SIM signal to match the SIM specifications: the connections
should always be kept as short as possible.
Avoid coupling with any sensitive analog circuit, since the SIM signals can cause the radiation of some harmonics
of the digital data frequency.
UBX-16010573 - R12
3V8
4PDT
C11
Analog
Switch
VCC
1VSIM
VSIM
2VSIM
1DAT
DAT
2DAT
1CLK
CLK
2CLK
1RST
RST
2RST
SEL
GND
U1
R1
LARA-R2 series - System Integration Manual
C1 C2 C3 C4 C5
D1 D2 D3 D4
C6 C7 C8 C9 C10
D5 D6 D7 D8
Part Number - Manufacturer
GRM1555C1H330JZ01 - Murata
GRM155R71C104KA01 - Murata
PESD0402-140 - Tyco Electronics
RC0402JR-0747KL- Yageo Phycomp
Various Manufacturers,
C707 10M006 136 2 - Amphenol
FSA2567 - Fairchild Semiconductor
FIRST
SIM CARD
VPP (C6)
VCC (C1)
IO (C7)
CLK (C3)
RST (C2)
GND (C5)
J1
SECOND
SIM CARD
VPP (C6)
VCC (C1)
IO (C7)
CLK (C3)
RST (C2)
GND (C5)
J2
Design-in
Page 102 of 157