SARA-G450 - System integration manual
UBX-18046432 - R08 Design-in Page 88 of 143
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2.5.1.4 Guidelines for single SIM card connection with detection
An application circuit for the connection to a single removable SIM card placed in a SIM card holder is
described in Figure 45, where the optional SIM card detection feature is implemented.
Follow these guidelines connecting the module to a SIM connector implementing SIM presence
detection:
Connect the UICC / SIM contact C1 (VCC) to the VSIM pin of the module.
Connect the UICC / SIM contact C7 (I/O) to the SIM_IO pin of the module.
Connect the UICC / SIM contact C3 (CLK) to the SIM_CLK pin of the module.
Connect the UICC / SIM contact C2 (RST) to the SIM_RST pin of the module.
Connect the UICC / SIM contact C5 (GND) to GND.
Connect one pin of the normally-open mechanical switch integrated in the SIM connector (as the
SW2 pin in Figure 45) to the SIM_DET input pin, providing a weak pull-down resistor (e.g. 470 kΩ,
as R2 in Figure 45).
Connect the other pin of the normally-open mechanical switch integrated in the SIM connector
(SW1 pin in Figure 45) to V_INT 1.8 V / 3 V supply output by means of a strong pull-up resistor (e.g.
1 kΩ, as R1 in Figure 45).
Provide a 1 µF bypass capacitor (e.g. Murata GRM155R70J105K) at the SIM supply line (VSIM),
close to the related pad of the SIM connector, to prevent digital noise.
Provide a bypass capacitor of about 22 pF to 33 pF (e.g. Murata GRM1555C1H330J) on each SIM
line (VSIM, SIM_CLK, SIM_IO, SIM_RST), very close to each related pad of the SIM connector, to
prevent RF coupling especially in case the RF antenna is placed closer than 10 – 30 cm from the
SIM card holder.
Provide a low capacitance (i.e. less than 1 pF) ESD protection (e.g. Tyco Electronics PESD0402-140)
on each externally accessible SIM line, close to each related pad of the SIM connector: the ESD
sensitivity rating of SIM interface pins is 1 kV (HBM according to JESD22-A114), so that, according
to EMC/ESD requirements of the custom application, a higher protection level can be required if
the lines are externally accessible.
Limit capacitance and series resistance on each SIM signal to match the requirements for the SIM
interface regarding maximum allowed rise time on the lines.
SARA-G450
41
VSIM
39
SIM_IO
38
SIM_CLK
40
SIM_RST
4
V_INT
42
SIM_DET
SIM CARD
HOLDER
C
5
C
6
C
7
C
1
C
2
C
3
SIM card
bottom view
(contacts side)
C1
VPP (C6)
VCC (C1)
IO (C7)
CLK (C3)
RST (C2)
GND (C5)
C2 C3 C5
J1
C4
SW1
SW2
D1 D2 D3 D4 D5 D6
R2
R1
C
8
C
4
TP
Figure 45: Application circuit for the connection to a single removable SIM card, with SIM detection implemented
Part number – Manufacturer
33 pF capacitor ceramic C0G 0402 5% 50 V
GRM1555C1H330JA01 – Murata
1 µF capacitor ceramic X7R 0402 10% 16 V
GRM155R70J105KA12 – Murata
Very low capacitance ESD protection
PESD0402-140 – Tyco Electronics
1 k resistor 0402 5% 0.1 W
RC0402JR-071KL – Yageo Phycomp
470 k resistor 0402 5% 0.1 W
RC0402JR-07470KL- Yageo Phycomp
SIM card holder
6 + 2 positions, with card presence switch
Generic manufacturer,
CCM03-3013LFT R102 – C&K Components
Table 30: Examples of components for the connection to a single removable SIM card, with SIM detection implemented
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