ZED-F9K - Integration manual
Pin no.
Name
I/O
Description
53
TIMEPULSE
O
Time pulse
54
Reserved
-
Reserved
Table 23: ZED-F9K pin assigment
4.2 Power supply
The u-blox ZED-F9K 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-F9K Data sheet [
] 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-F9K
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-F9K 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
The V_BCKP pin can be used to provide power to maintain the real-time clock (RTC) and battery-
backed RAM (BBR) when VCC is removed.
V_BCKP can be provided with a battery. If V_BCKP is provided during a VCC outage, the receiver may
be able to perform a hot or warm start. Especially if the RTC and BBR contents are still current, i.e.
after a short VCC outage. The fusion filter data is also stored in BBR and ZED-F9K can restart in
fusion mode.
If V_BCKP is not provided, the module performs a cold start at power up. Also sensors will need to
be recalibrated.
If a host is connected to ZED-F9K, V_BCKP can be partially emulated by using UBX-UPD-SOS
functionality. BBR data can saved to the host and restored at startup. See
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.
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
UBX-20046189 - R01
4 Design
Page 74 of 105
C1-Public
Early production information
