SARA-G450 - System integration manual
UBX-18046432 - R08 Design-in Page 102 of 143
C1-Public
Figure 64 illustrates an alternative solution as supply for u-blox 1.8 V GNSS receivers: the V_INT 1.8 V
regulated supply output of SARA-G450 cellular modules can be used to supply a u-blox 1.8 V GNSS
receiver instead of using an external voltage regulator as shown in the previous Figure 63. 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 1.8 V (V_INT = 1.8 V, if VSEL pin is
connected to GND; see 1.5.3) when the cellular module is switched on and it is disabled when the
module is switched off.
The supply of the u-blox 1.8 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 Figure 64,
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 1.8 V GNSS receiver, so that it will be switched on when
V_INT output is enabled.
SARA-G450
(1.8 V)
u-blox GNSS
1.8 V receiver
V_BCKP V_BCKP
2
SDA2
SCL2
23
GPIO2
SDA
SCL
26
27
VCC
1V8
C1
R3
4
V_INT
R5
R4
TP
T2
T1
R1 R2
1V8 1V8
GNSS supply enable
21
VSEL
Figure 64: Application circuit for connecting SARA-G450 (1.8 V) modules to u-blox 1.8 V GNSS receivers using V_INT as supply
Part number - Manufacturer
4.7 k resistor 0402 5% 0.1 W
RC0402JR-074K7L - Yageo Phycomp
47 k resistor 0402 5% 0.1 W
RC0402JR-0747KL - Yageo Phycomp
10 k resistor 0402 5% 0.1 W
RC0402JR-0710KL - Yageo Phycomp
100 k resistor 0402 5% 0.1 W
RC0402JR-07100KL - Yageo Phycomp
P-channel MOSFET low on-resistance
IRLML6401 - International Rectifier or NTZS3151P - ON Semi
100 nF capacitor ceramic X7R 0402 10% 16 V
GRM155R71C104KA01 - Murata
Table 38: Components for connecting SARA-G450 (1.8 V) modules to u-blox 1.8 V GNSS receivers using V_INT as supply
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