Power Management; Power Modes - Ublox ZOE-M8B Series System Integration Manual

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.
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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
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If no backup supply is available, V_BCKP can be connected to reserved neighbor pin G9.
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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.
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For description of the different power operating modes see the

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
UBX-17045131 - R04
Production Information
ZOE-M8B - System Integration Manual
Contents
ZOE-M8B Data Sheet [1].
Page 12 of 42