Ublox LISA-U100, Integration Manual

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LISA-U series - System Integration Manual
UBX-13001118 - R17 Advance information System description
Page 91 of 190
or a warm start (depending on the duration of the GNSS
VCC
outage) and to maintain the configuration
settings saved in the backup RAM.
“GNSS data ready” and “GNSS RTC sharing” functions are not supported by all u-blox GNSS receivers
HW or ROM/FW versions. See the
GNSS Implementation Application Note [17] or to the Hardware
Integration Manual of the u-blox GNSS receivers for the supported features.
LISA-U series
(except LISA-U200-00S)
R1
IN OUT
GND
GPS LDO
Regulator
SHDN
u-blox GNSS
1.8 V receiver
SDA2
SCL2
R2
1V8 1V8
VMAIN 1V8
U1
21
GPIO2
SDA
SCL
C1
TxD1
EXTINT0
GPIO3
GPIO4
46
45
23
24
VCC
R3
V_BCKP V_BCKP 2
R4
Figure 49: DDC Application circuit for u-blox 1.8 V GNSS receiver
Reference Description Part Number - Manufacturer
R1, R2, R4 4.7 k Ω Resistor 0402 5% 0.1 W RC0402JR-074K7L - Yageo Phycomp
R3 47 k Ω Resistor 0402 5% 0.1 W RC0402JR-0747KL - Yageo Phycomp
U1 Voltage Regulator for GNSS receiver See GNSS receiver Hardware Integration Manual
Table 39: Components for DDC application circuit for u-blox 1.8 V GNSS receiver
As an alternative to using an external voltage regulator, the
V_INT
supply output of LISA-U 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 power saving configuration enabled by AT+UPSV (see the
u-blox AT Commands Manual [3]).
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 newer 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 [17] for additional guidelines using the
V_INT
supply output of
LISA-U cellular modules to supply a u-blox 1.8 V GNSS receiver.