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As an alternative to using an external voltage regulator, the V_INT supply output of SARA-G350 wireless
modules can be used to supply a u-blox 1.8 V GNSS receiver of the u-blox 6 family (or later u-blox
family). The V_INT supply is able to withstand the maximum current consumption of these positioning
receivers.
The V_INT supply output provides low voltage ripple (up to 15 mVpp) when the module is in active-
mode or in connected-mode, but it provides higher voltage ripple (up to 90 mVpp) when the module is
in the low power idle-mode with power saving configuration enabled by AT+UPSV (refer to
Commands Manual
[2]).
According to the voltage ripple characteristic of the V_INT supply output:
The power saving configuration cannot be enabled to properly supply by V_INT output any 1.8 V
GNSS receiver of the u-blox 6 family and any 1.8 V GNSS receiver of the u-blox 7 family with
TCXO
The power saving configuration can be enabled to properly supply by V_INT output any 1.8 V GNSS
receiver of the u-blox 7 family without TCXO
Additional filtering may be needed to properly supply an external LNA, depending on the characteristics
of the used LNA, adding a series
BLM15HD182SN1 ferrite bead and the Murata GRM1555C1H220J 22 pF capacitor) at the input of the
external LNA supply line.
GNSS Implementation Application Note
Refer to the
output of SARA-G350 wireless modules to supply a u-blox 1.8 V GNSS receiver.
Figure 56Figure 56
illustrates the application circuit for SARA-G350 connection to a u-blox 3.0 V GNSS
receiver:
SDA and SCL pins of SARA-G350 are directly connected to the related pins of the u-blox 3.0 V
GNSS receiver, with appropriate pull-up resistors: an I2C-bus Voltage Translator is not needed
because SARA-G350 DDC (I
GPIO3 and GPIO4 pins of SARA-G350 are connected to the u-blox 3.0 V GNSS receiver by means
of a general purpose Voltage Translator, needed for SARA-G350 generic digital pins because only 1.8
V capable.
GPIO2 is connected to the active-high enable pin of the external voltage regulator that supplies the
u-blox 3.0 V GNSS receiver to enable or disable the 3.0 V GNSS supply.
The V_BCKP supply output of SARA-G350 is directly connected to the V_BCKP backup supply input
pin of the u-blox 3.0 V GNSS receiver as in the application circuit for a u-blox 1.8 V GNSS
receiver.
UBX-13000995 - R06
SARA-G3 series - System Integration Manual
ferrite bead and a bypass capacitor (e.g. the Murata
[21] for additional guidelines using the V_INT supply
2
C) pins are capable up to 3.3 V.
Objective Specification
u-blox AT
Design-in
Page 138 of 218
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