SARA-G3 and SARA-U2 series - System Integration Manual
UBX-13000995 - R08
Objective Specification
Design-in
Page 138 of 188
2.8
General Purpose Input/Output (GPIO)
2.8.1.1
Guidelines for GPIO circuit design
The following application circuits are suggested as a general guideline for the usage of the GPIO pins available
with the SARA-G340 / SARA-G350 and SARA-U2 series modules, according to the related custom function.
Figure 80 describes an application circuit for a typical usage of some GPIO functions of the modules:
Network indication function provided by the
GPIO1
pin
GNSS supply enable function provided by the
GPIO2
pin
GNSS data ready function provided by the
GPIO3
pin
GNSS RTC sharing function provided by the
GPIO4
pin
OUT
IN
GND
LDO Regulator
SHDN
3V8
1V8
GPIO3
GPIO4
TxD1
EXTINT0
24
25
R1
VCC
GPIO2
23
SARA-G340 / SARA-G350
SARA-U2 series
u-blox GNSS
1.8 V receiver
U1
C1
R2
R4
3V8
Network Indicator
R3
GNSS Supply Enable
GNSS Data Ready
GNSS RTC Sharing
16
GPIO1
DL1
T1
Figure 80: GPIO application circuit
Reference
Description
Part Number - Manufacturer
R1
47 k
Ω
Resistor 0402 5% 0.1 W
Various manufacturers
U1
Voltage Regulator for GNSS receiver
See GNSS module Hardware Integration Manual
R2
10 k
Ω
Resistor 0402 5% 0.1 W
Various manufacturers
R3
47 k
Ω
Resistor 0402 5% 0.1 W
Various manufacturers
R4
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 45: Components for GPIO application circuit
Use transistors with at least an integrated resistor in the base pin or otherwise put a 10 k
Ω
resistor on the
board in series to the GPIO.
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 on the application board.
Higher protection level can be achieved by mounting an ESD protection (e.g. EPCOS CA05P4S14THSG
varistor array) close to accessible points.
