Integration Manual

SARA-R4/N4 series - System Integration Manual
UBX-16029218 - R13 Design-in Page 82 of 119
• Module operating status indication provided by a GPIO pin (see section 1.6.1)
• SIM card detection provided over GPIO5 pin (see Figure 39 / Table 28 in section 2.5)
SARA-R4/ N4
GPIO1
R1
R3
3V8
Net work Indicat or
R2
16
DL1
T1
Figure 53: Application circuit for network indication provided over GPIO1
Reference Description Part Number - Manufacturer
R1
10 kΩ Resistor 0402 5% 0.1 W
Various manufacturers
R2
47 kΩ Resistor 0402 5% 0.1 W
Various manufacturers
R3
820 Ω Resistor 0402 5% 0.1 W
Various manufacturers
DL1 LED Red SMT 0603 LTST-C190KRKT - Lite-on Technology Corporation
T1 NPN BJT Transistor BC847 - Infineon
Table 36: Components for network indication application circuit
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☞ Use transistors with at least an integrated resistor in the base pin or otherwise put a 10 kΩ resistor on the board in
series to the GPIO of SARA-R4/N4 series modules.
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☞ Do not apply voltage to any GPIO of the module before the switch-on of the GPIOs supply (V_INT), to avoid latch-up
of circuits and allow a clean module boot. If the external signals connected to the module cannot be tri-stated or set
low, insert a multi-channel digital switch (e.g. TI SN74CB3Q16244, TS5A3159, TS5A63157) between the two-circuit
connections and set to high impedance before V_INT switch-on.
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☞ ESD sensitivity rating of the GPIO pins is 1 kV (Human Body Model according to JESD22-A114).
Higher protection level could be required if the lines are externally accessible and it can be achieved by mounting an
ESD protection (e.g. EPCOS CA05P4S14THSG varistor array) close to accessible points.
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☞ If the GPIO pins are not used, they can be left unconnected on the application board.
2.8.2 Guidelines for general purpose input/output layout design
The general purpose inputs / outputs pins are generally not critical for layout.