LENA-R8 series - System integration manual
UBX-22015376 - R02
Design-in
Page 72 of 116
C1-Public
Guidelines for dual SIM card / chip connection
Two SIM cards / chips can be connected to LENA-R8 series
modules’
SIM interface as in
LENA-R8 series modules do not support the usage of two SIMs at the same time, but two SIMs can
be populated on the application board, providing a proper switch to connect only the first or only the
second SIM at a time to the SIM interface of the modules, as described in
In the application circuit example represented in
, the application processor will drive the SIM
switch using its own GPIO to properly select the SIM that is used by the module, when the SIM
interface of the module is disabled, as when the module cellular system is switched off.
The dual SIM connection circuit described in
can be implemented for SIM chips as well,
providing proper connection between SIM switch and SIM chip as described in
If it is required to switch between more than 2 SIM, a circuit like the one described in
can be
implemented: for a 4 SIM circuit, using proper 4-throw switch instead of the suggested 2-throw
switches.
Follow these guidelines connecting the module to two SIM connectors:
•
Use a proper low on resistance (i.e. few ohms) and low on capacitance (i.e. few pF) 2-throw analog
switch (e.g. Fairchild FSA2567) as SIM switch to ensure high-speed data transfer according to
SIM requirements.
•
Connect the contacts C1 (VCC) of the two UICC / SIM to the
VSIM
pin of the module by means of
a proper 2-throw analog switch (e.g. Fairchild FSA2567).
•
Connect the contact C7 (I/O) of the two UICC / SIM to the
SIM_IO
pin of the module by means of a
proper 2-throw analog switch (e.g. Fairchild FSA2567).
•
Connect the contact C3 (CLK) of the two UICC / SIM to the
SIM_CLK
pin of the module by means
of a proper 2-throw analog switch (e.g. Fairchild FSA2567).
•
Connect the contact C2 (RST) of the two UICC / SIM to the
SIM_RST
pin of the module by means
of a proper 2-throw analog switch (e.g. Fairchild FSA2567).
•
Connect the contact C5 (GND) of the two UICC / SIM to ground.
•
Provide a 100 nF bypass capacitor (e.g. Murata GRM155R71C104K) at the SIM supply line (
VSIM
),
close to the related 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 related 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. Littelfuse PESD0402-
140) on each externally accessible SIM line, close to each related 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 to match the SIM specifications (as
for example, 1.0
µ
s is the max allowed rise time on
SIM_IO
and
SIM_RST
).