ZED-F9P-Integration manual
Pin No Name I/O Description
52 Reserved - Reserved
53 TIMEPULSE O Time pulse
54 Reserved - Reserved
Table 30: ZED-F9P pin assignment
4.2 Power supply
The u-blox ZED-F9P module has three power supply pins: VCC, V_BCKP and V_USB.
4.2.1 VCC: Main supply voltage
The VCC pin is connected to the main supply voltage. During operation, the current drawn by the
module can vary by some orders of magnitude. For this reason, it is important that the supply
circuitry be able to support the peak power for a short time (see the ZED-F9P Data sheet [1] for
specification).
The module integrates a DC/DC converter, which allows reduced power consumption.
When switching from backup mode to normal operation or at start-up, u-blox ZED-F9P
modules must charge the internal capacitors in the core domain. In certain situations, this
can result in a significant current draw. For low-power applications using backup mode, it is
important that the power supply or low ESR capacitors at the module input can deliver this
current/charge.
To reduce peak current during power on, users can employ an LDO that has an in-built
current limiter.
Do not add any series resistance greater than 0.2
Ω
to the VCC supply as it will generate
input voltage noise due to dynamic current conditions.
For the ZED-F9P module the equipment must be supplied by an external limited power
source in compliance with the clause 2.5 of the standard IEC 60950-1.
4.2.2 V_BCKP: Backup supply voltage
If the module supply has a power failure, the V_BCKP pin supplies the real-time clock (RTC) and
battery backed RAM (BBR). Use of valid time and the GNSS orbit data at start up will improve the
GNSS performance, as with hot starts and warm starts.
If V_BCKP is not provided, the module performs a cold start at power up.
If a host is connected to ZED-F9P, V_BCKP can be partially emulated by using UBX-UPD-SOS
functionality. BBR data can saved to the host and restored at startup. See Interface description for
more information.
Avoid high resistance on the V_BCKP line: During the switch from main supply to backup
supply, a short current adjustment peak can cause a high voltage drop on the pin with
possible malfunctions.
Add a 2 uF capacitor on the V_BCKP pin to absorb the current adjustment peak when
switching from VCC to V_BCKP supply.
If no backup supply voltage is available, connect the V_BCKP pin to VCC.
Allow all I/O including UART and other interfaces to float or connect to a high impedance in
HW backup mode (V_BCKP supplied when VCC is removed). See the Interfaces section.
Real time clock (RTC)
UBX-18010802 - R08
4 Design Page 73 of 110
Early production information
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