User's Manual

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Note d’étude / Technical document : URD1– OTL 5665.1– 002 / 70 884 Edition 03
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3.8 GPIO
There are five GPIOs available on HiloNC. The GPIO1, GPIO2 and GPIO3 have internal pull-up resistors while
GPIO4 and GPIO5 are open collector.
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If GPIO4 and GPIO5 are used as output, they must be pulled up to VGPIO. The typical value of the pull-up
resisters is 100K ohms.
3.9 BACKUP BATTERY
3.9.1 Backup battery function feature
3.9.1.1 With backup battery
A backup battery can be connected to the module in order to supply internal RTC (Real Time Clock) when the
main power supply is removed. Thus, when the main power supply is removed, the RTC is still supplied and the
module keeps the time running.
With external backup battery:
- If VBAT < 3V, internal RTC is supplied by VBACKUP.
- If VBAT > =3V, internal RTC is supplied by VBAT.
3.9.1.2 Without backup battery
Without backup battery
- If VBAT > 1.5V, internal RTC is supplied by VBAT.
- If VBAT < 1.5V, internal RTC is not supplied.
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VBACKUP input of the module has to be connected to a 10µF capacitor (between VBACKUP and GND).
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SAGEM does not recommend to connect VBACKUP signal to VBAT. However, if VBACKUP has been
connected to VBAT, this has no influence if VBAT is between 3.2V and 4.2V. For VBAT above 4.2V the module
can take a longer time to start at low temperature.
3.9.2 Current consumption on the backup battery
When the power supply is removed, the internal RTC will be supplied by backup battery.
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To calculate the backup battery capacity, consider that Current consumption for RTC on the backup
battery is below 2,6µA depending on the temperature.
Pin Name Min Max
VBACKUP 2.6µA
3.9.3 Charge by internal HiloNC charging function
The charging function is available on the HiloNC without any additional external power supply (the charging
power supply is provided by the HiloNC).
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Charge of the back-up battery occurs only when main power supply VBAT is provided.
The recommended schematic is given hereafter: