Figure 3: Internal Power Supply
3.2. Power Supply
3.2.1. VCC
The VCC pin supplies power for BB, RF, and RTC domain. VCC pin load current varies according to VCC
voltage level, processor load and satellite acquisition state.
Module power consumption may vary in several orders of magnitude, especially when low power mode is
enabled. Therefore, it is important that the power supply can sustain peak power for a short time, ensuring
that the load current does not exceed the rated value. When the modules switch from Backup mode to
normal operation or startup, it must charge the internal capacitors in the core domain. In some cases, this
can lead to a significant current drain.
For low-power applications using power saving and backup modes, it is important that the LDO at the
power supply or module input can provide the current/drain. An LDO with a high PSRR should be chosen
for good performance. In addition, a TVS diode, and a combination of a 10 μF, 100 nF and a 33 pF
decoupling capacitor network should be added near the VCC pin. The lowest value capacitor should be
the closest to module pins.
It is not recommended to use a switching DC-DC power supply.
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