FALCOM I56 Hardware Description page 36

I65/I56I HARDWARE DESCRIPTION
Li-Ion battery pack specified for a maximum charging voltage of 4.2 V
and a capacity of 800 mAh. Battery packs with a capacity down to 600
mAh or more than 800 mAh are allowed, too.
Since charging and discharging largely depend on the battery
temperature, the battery pack should include a NTC resistor. If the NTC
is not inside the battery it must be in thermal contact with the battery.
The NTC resistor must be connected between BAT_TEMP and GND.
Required NTC characteristics are: 10 kΩ + 5 % @ 25 °C, B25/85 =
3435 K + 3 % (alternatively acceptable: 10 kΩ + 2 % @ 25 °C, B25/50 =
3370 K + 3 %).
Please note that the NTC is indispensable for proper charging, i.e. the
charging process will not start if no NTC is present.
Ensure that the pack incorporates a protection circuit capable of detecting
over voltage (protection against overcharging), under voltage (protection
against deep discharging) and over current. The circuit must be
insensitive to pulsed current.
On the I56/I56i module, a built-in measuring circuit constantly monitors
the supply voltage. In the event of under voltage, it causes I56/I56i to
power down. Under voltage thresholds are specific to the battery pack
and must be evaluated for the intended model. When you evaluate under
voltage thresholds, consider both the current consumption of I56/I56i and
of the application circuit.
The internal resistance of the battery and the protection should be as low
as possible. It is recommended not to exceed 150 mΩ, even in extreme
conditions at low temperature. The battery cell must be insensitive to
rupture, fire and gassing under extreme conditions of temperature and
charging (voltage, current).
The battery pack must be protected from reverse pole connection. For
example, the casing should be designed to prevent the user from
mounting the battery in reverse orientation.
The battery pack must be approved to satisfy the requirements of CE
conformity.
Figure 8 below shows the circuit diagram of a typical battery pack design that
includes the protection elements described above.
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VERSION 1.00
Page 36