ZOE-M8B - System Integration Manual
UBX-17045131 - R04
Contents
Page 12 of 42
Production Information
2
Design-in
In order to obtain good performance with the ZOE-M8B GNSS SiP, there are a number of issues
requiring careful attention during the design-in. These include:
•
Power Supply
: Good performance requires a clean and stable power supply.
•
Interfaces
: Ensure correct wiring, rate and message setup on the SiP and your host system.
•
Antenna interface
: For optimal performance, seek short routing, matched impedance and no
stubs.
2.1
Power management
2.1.1
Overview
The ZOE-M8B GNSS SiP provides two supply pins:
VCC
and
V_BCKP
. They can be supplied
independently or tied together, depending on the intended application.
2.1.1.1
Main supply voltage (VCC)
During operation, the ZOE-M8B GNSS SiP receives power through the
VCC
pin. Built-in LDOs generate
stabilized voltages for the core and RF domains of the chip. The current at
VCC
depends heavily on
the current state of the system and is in general very dynamic.
☞
Do not add any series resistance (< 0.1
Ω
) to the
VCC
supply, as it will generate input voltage noise
due to the dynamic current conditions.
The digital I/Os of the ZOE-M8B GNSS SiP are supplied by the
VCC
voltage.
2.1.1.2
Backup power supply (V_BCKP)
In the case of a power failure at main supply
VCC
, the backup domain and optional RTC oscillator are
supplied by
V_BCKP
. Providing a
V_BCKP
supply maintains the time (RTC) and the GNSS orbit data
in backup RAM. This ensures that any subsequent re-starts after a
VCC
power failure will benefit from
the stored data, providing a faster TTFF.
The GNSS satellite ephemeris data is typically valid for up to 4 hours. To enable hot starts, ensure
that the battery or capacitor at
V_BCKP
is able to supply the backup current for at least 4 hours. For
warm starts or when using the AssistNow Autonomous, the
V_BCKP
source must be able to supply
current for up to a few days
☞
If no backup supply is available,
V_BCKP
can be connected to reserved neighbor pin G9.
☞
Avoid high resistance on the
V_BCKP
line: During the switch from main supply to backup supply,
a short current adjustment peak can cause high voltage drop on the pin with possible
malfunctions.
☞
For description of the different power operating modes see the
ZOE-M8B Data Sheet [1].
2.1.2
Power Modes
The ZOE-M8B GNSS SiP can operate in two power modes:
•
Super-E Mode to optimize power consumption (default mode)
•
Continuous Mode for best GNSS reception
The available power modes are illustrated in Figure 9. The Super-E Mode has three predefined
settings for 1 Hz (default), 2 Hz and 4 Hz update rates. In addition, Super-E mode supports longer
