Ublox SARA-N2 Series, System Integration Manual

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SARA-N2 / N3 series - System integration manual
UBX-17005143 - R13 Design-in Page 58 of 95
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• Connect one pin of the normally-open mechanical switch integrated in the SIM connector (as the
SW2 pin in
Figure 32 ) to the GPIO5 input pin, providing a weak pull-down resistor (e.g. 470 k

, as
R2 in Figure 32 ).
• Connect the other pin of the normally-open mechanical switch integrated in the SIM connector
(SW1 pin in
Figure 32 ) to V_INT 1.8 V supply output by means of a strong pull-up resistor (e.g. 1 k  ,
as R1 in Figure 32 )
•
Provide a 100 nF bypass capacitor (e.g. Murata GRM155R71C104K) 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 GCM1555C1H330JA16) 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 the EMC/ESD requirements of the custom application, 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 (18.7 ns = maximum rise time on
SIM_CLK , 1.0
µ
s = maximum rise time on SIM_IO and
SIM_RST ).
SARA-N3
41
VSIM
39
SIM_IO
38
SIM_CLK
40
SIM_RST
4
V_INT
42
GPIO5
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 32: Application circuit for the connection to a single removable SIM card, with SIM detection implemented
Reference Description Part number - Manufacturer
C1, C2, C3, C4 33 pF capacitor ceramic C0G 0402 5% 50 V GCM1555C1H330JA16 - Murata
C5 100 nF capacitor ceramic X7R 0402 10% 16 V GCM155R71C104KA55 - Murata
D1
–
D6 Very low capacitance ESD protection PESD0402-140 - Tyco Electronics
R1
1 k  resistor 0402 5% 0.1 W
RC0402JR-071KL - Yageo Phycomp
R2 470 k  resistor 0402 5% 0.1 W RC0402JR-07470KL- Yageo Phycomp
J1 SIM card holder
6 + 2 positions, with card presence switch Various manufacturers,
CCM03-3013LFT R102 - C&K Components
Table 22: Example of components for the connection to a single removable SIM card, with SIM detection implemented