SARA-G450 - System integration manual
UBX-18046432 - R08
Design-in
Page 105 of 143
C1-Public
illustrates an alternative solution as supply for u-blox 3.0 V GNSS receivers: the V_INT 3.0 V
regulated supply output of SARA-G450 cellular modules can be used to supply a u-blox 3.0 V GNSS
receiver instead of using an external voltage regulator as shown in the previous
. The V_INT
supply is able to support the maximum current consumption of these positioning receivers.
The internal LDO that generates the V_INT supply is set to 3.0 V (V_INT = 3 V, if VSEL pin is left
unconnected; see
) when the cellular module is switched on and it is disabled when the module is
switched off.
The supply of the u-blox 3.0 V GNSS receiver can be switched off using an external p-channel MOSFET
controlled by the GPIO2 pin by means of an appropriate inverting transistor as shown in
implementing the “GNSS supply enable” function. If this feature is not required, the V_INT supply
output can be directly connected to the u-blox 3.0 V GNSS receiver, so that it will be switched on when
V_INT output is enabled.
SARA-G450
(3.0 V)
u-blox GNSS
3.0 V receiver
V_BCKP
V_BCKP
2
SDA2
SCL2
23
GPIO2
SDA
SCL
26
27
VCC
3V0
C1
R3
4
V_INT
R5
R4
TP
T2
T1
R1
R2
3V0 3V0
GNSS supply enable
21
VSEL
Figure 67: Application circuit for connecting SARA-G450 (3.0 V) modules to u-blox 3.0 V GNSS receivers using V_INT as
supply
Reference Description
Part number - Manufacturer
R1, R2
4.7 k
resistor 0402 5% 0.1 W
RC0402JR-074K7L - Yageo Phycomp
R3
47 k
resistor 0402 5% 0.1 W
RC0402JR-0747KL - Yageo Phycomp
R4
10 k
resistor 0402 5% 0.1 W
RC0402JR-0710KL - Yageo Phycomp
R5
100 k
resistor 0402 5% 0.1 W
RC0402JR-07100KL - Yageo Phycomp
T1
P-channel MOSFET low on-resistance
IRLML6401 - International Rectifier or NTZS3151P - ON Semi
T2
NPN BJT transistor
BC847 - Infineon
C1
100 nF capacitor ceramic X7R 0402 10% 16 V
GRM155R71C104KA01 - Murata
Table 41: Components for connecting SARA-G450 (3.0 V) modules to u-blox 3.0 V GNSS receivers using V_INT as supply