Installation Instructions

LISA-U2 series - System Integration Manual
UBX-13001118 - R19 Early Production Information System description
Page 34 of 175
the VCC supply has been provided. The purpose of the series diode is to avoid a current flow from the module
V_BCKP pin to the non-rechargeable battery.
Combining a LISA-U2 series cellular module with a u-blox GNSS receiver, the VCC supply of the GNSS receiver is
controlled by the cellular module by means of the “GNSS supply enable” function provided by the GPIO2 of the
cellular module. In this case the V_BCKP supply output of the LISA-U2 series cellular module can be connected
to the V_BCKP backup supply input pin of the GNSS receiver to provide the supply for the GNSS real time clock
and backup RAM when the VCC supply of the cellular module is within its operating range and the VCC supply
of the GNSS receiver is disabled. This enables the u-blox GNSS receiver to recover from a power breakdown with
either a hotstart or a warmstart (depending on the duration of the GNSS VCC outage) and to maintain the
configuration settings saved in the backup RAM. See the section 1.10 for more details regarding the application
circuit with a u-blox GNSS receiver.