Integration Manual

LISA-U2 series - System Integration Manual
UBX-13001118 - R25 System description Page 90 of 182
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 [2]).
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 [15] 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.