SARA-G450 - System integration manual
UBX-18046432 - R08
Design-in
Page 112 of 143
C1-Public
2.8
General Purpose Input/Output (GPIO)
2.8.1.1
Guidelines for GPIO circuit design
The following application circuit is suggested as a general guideline for the usage of the GPIO pins
available with the SARA-G450 modules, according to the related custom function.
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
19
OUT
IN
GND
LDO regulator
SHDN
3V8
1V8
R1
VCC
GPIO2
23
SARA-G450
u-blox GNSS
1.8 V receiver
U1
C1
R2
R4
3V8
Network indication
R3
GNSS supply enable
16
GPIO1
DL1
T1
Figure 71: GPIO application circuit
Reference
Description
Part number - Manufacturer
R1
47 k
Ω
resistor 0402 5% 0.1 W
Generic manufacturer
U1, C1
Voltage regulator for GNSS receiver and related
output bypass capacitor
See GNSS module hardware integration manual
R2
10 k
Ω
resistor 0402 5% 0.1 W
Generic manufacturer
R3
47 k
Ω
resistor 0402 5% 0.1 W
Generic manufacturer
R4
820
Ω
resistor 0402 5% 0.1 W
Generic manufacturer
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.
☞
The ESD sensitivity rating of the GPIO pins is 1 kV (Human Body Model according to JESD22-A114).
A higher protection level could be required if the lines are externally accessible on the application
board. This higher protection level can be achieved by mounting an ESD protection (e.g. EPCOS
CA05P4S14THSG varistor array) close to accessible points.
19
Not supported by the “00” product version