User's Manual

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Note d’étude / Technical document : URDx– OTL 5635.1– 007 / 70 230 Edition 03

Document Sagem Communications Reproduction et divulgation interdites

Sagem Communications document. Reproduction and disclosure prohibited

If there is no backup battery, VBACKUP input of the module has to be connected to VBAT signal.

Without external VBACKUP (VBACKUP input connected to VBAT)

- If VBAT > 1.5V, internal RTC is supplied by VBAT.

- If VBAT < 1.5V, internal RTC is not supplied.

Pin Name Min Max Remarks

VBACKUP +1.5V +3.18V Protection

3.9.2 Current consumption on the backup battery

When the power supply is removed, the internal RTC will be supplied by backup battery.

3.9.3 Charge by internal HiLo charging function

The charging function is available on the HiLo without any additional external power supply (the charging power

supply is provided by the HiLo).

The recommended schematic is given hereafter:

Figure 15: Backup battery internally charged

The resistor R depends on the charging current value provided by the battery manufacturer.

The charging curve which is done by the HiLo is given hereafter:

Figure 16: Charging curve of backup battery

3.9.4 Backup Battery technology recommended

3.9.4.1 Manganese Silicon Lithium-Ion rechargeable Battery

Sagem communications does not recommend using this kind of technology because of the following drawbacks:

• The maximum discharge current is limited (Shall be compliant with the module characteristics)

VBACKUP

HiLo