SARA-G450 - System integration manual
UBX-18046432 - R08 Design-in Page 113 of 143
C1-Public
☞ Any external signal connected to the GPIOs must be tri-stated or set low when the module is in
power-off mode and during the module power-on sequence (at least until the settling of the V_INT
supply output of the module to the configured 1.8 V / 3 V value), to avoid latch-up of circuits and
allow a clean boot of the module. If the external signals connected to the module cannot be
tri-stated or set low, insert a multi-channel digital switch (e.g. Texas Instruments
SN74CB3Q16244, TS5A3159, or TS5A63157) between the two-circuit connections and set to high
impedance during module power-off mode and power-on sequence.
☞ If the GPIO pins are not used, they can be left unconnected on the application board.
2.8.1.2 Guidelines for GPIO layout design
The general purpose input/output pins are generally not critical for layout.
2.9 Reserved pins (RSVD)
SARA-G450 modules have pins reserved for future use, marked as RSVD.
All the RSVD pins can be left unconnected on the application board, except for the RSVD pin #33 that
can be externally connected to GND or left unconnected too.
2.10 Module placement
Optimize placement for minimum length of RF line and closer path from DC source for VCC.
Make sure that the module, RF and analog parts / circuits are clearly separated from any possible
source of radiated energy, including digital circuits that can radiate some digital frequency harmonics,
which can produce electromagnetic interference affecting module, RF and analog parts / circuits’
performance or implement suitable countermeasures to avoid any possible electromagnetic
compatibility issue.
Make sure that the module, RF and analog parts / circuits, high speed digital circuits are clearly
separated from any sensitive part / circuit which may be affected by electromagnetic interference or
employ countermeasures to avoid any possible electromagnetic compatibility issue.
Provide enough clearance between the module and any external part: clearance of at least 0.4 mm per
side is recommended to let suitable mounting of the parts.
☞ The heat dissipation during transmission at maximum power can raise the temperature of the
module and its environment, as the application board locations near and below the SARA-G450
modules: avoid placing temperature sensitive devices close to the module.
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