LISA-U2 series - System integration manual
UBX-13001118 - R27
System description
Page 90 of 183
C1-Public
As an alternative to using an external voltage regulator, the
V_INT
supply output of LISA-U2 cellular
modules can be used to supply a u-blox 1.8 V GNSS receiver of the u-blox 6 generation (or later u-blox
generation). 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 70 mVpp) when the module is
in the low-power idle mode with the power saving configuration enabled by AT+UPSV (see the u-blox
AT commands manual
According to the voltage ripple characteristic of the
V_INT
supply output:
•
The power saving configuration cannot be enabled to use
V_INT
output to properly supply any 1.8
V GNSS receiver of the u-blox 6 generation and any 1.8 V GNSS receiver of the u-blox 7 generation
or any newer u-blox GNSS receiver generation with TCXO.
•
The power saving configuration can be enabled to use
V_INT
output to properly supply any 1.8 V
GNSS receiver of the u-blox 7 generation or any more recent u-blox GNSS receiver generation
without TCXO.
•
Additional filtering may be needed to properly supply an external LNA, depending on the
characteristics of the used LNA, adding a series ferrite bead and a bypass capacitor (e.g. the
Murata BLM15HD182SN1 ferrite bead and the Murata GRM1555C1H220J 22 pF capacitor) at
the input of the external LNA supply line.
See the GNSS implementation application note
for additional guidelines on using the
V_INT
supply output of LISA-U2 cellular modules to supply a u-blox 1.8 V GNSS receiver.