User's Manual

page 28/51
HiAll
NC
User Manual 2012/06/28
3.8 ADCS
Two ADC input pads are available on HiAll
NC
module, which can be used to read the value of the voltage
applied. Following characteristics must be met to allow proper performances:
• The input signal voltage must be within 0V to 3V
• The input impedance of the pad is 150KΩ
• The input capacitance typically is 10pF.
• 10 bits resolution
• Maximum sampling frequency is 200KHz.
3.9 BACKUP BATTERY
3.9.1 Backup battery function features
A backup battery can be connected to the module in order to supply internal RTC (Real Time Clock) when the
main power supply is disconnected.
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With external backup battery:
• If VBAT < 3V, internal RTC is supplied by VBACKUP.
• If VBAT ≥3V, internal RTC is supplied by VBAT.
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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).
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 up to 1000µA in worst case conditions.
Signals Min current Max current
VBACKUP 1000µA
3.9.3 Internal HiAll
NC
charging function
HiAll
NC
has a charging function that does not require any additional external power supply (power supply for the
charging is provided by the HiAll
NC
).
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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: