MIA-M10Q - Integration manual
Figure 23: VCC and V_IO supplied by separate supplies, and external power supply at V_BCKP
Figure 24: VCC and V_IO supplied by separate supplies. No external power supply at V_BCKP.
3.2 Real-time clock
The real-time clock (RTC) is a part of the backup domain. The RTC is supplied by the V_IO, or by
the optional V_BCKP if V_IO is not present. The RTC is continuously calibrated when the receiver
has GNSS position fix. The RTC is used to maintain time during the backup modes and the ON/OFF
operation of the power save mode (PSMOO), or when V_IO is not present due to a power failure. Time
information is required for hot start, warm start, and for using AssistNow data.
The RTC can be implemented by connecting an external RTC crystal, by providing an external 32.768
kHz clock signal to the RTC input, or by sending time aiding at every startup. The ON/OFF operation
(PSMOO) and the software standby mode with a defined off period both require an RTC. For other
purposes, time aiding can be used.
3.2.1 RTC using a crystal oscillator
MIA-M10Q supports an external RTC crystal. The RTC crystal is connected between RTC_I
and RTC_O as shown in
. Adding external load capacitors for frequency tuning is not
recommended. An RTC crystal is the lowest-power option to maintain time in a backup mode. The
RTC crystal specification and recommended components are available in
.
The RTC oscillator has a startup margin of five for the specified ESR when no external load
capacitors are used. Adding external load capacitors reduces the startup margin.
RTC_I is a high-impedance input. Make sure the line to the RTC crystal is short and that no
other noisy signals are routed close to it.
UBX-21028173 - R01
3 Hardware integration
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