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4.4 Charging Interface
SIM808 has integrated a charging circuit inside the module for Li-Ion batteries charging control, which make it
very convenient for user’s applications that support battery charging. A common connection is shown in the
following figure:
Module
Battery
Pack
VBAT
VBUS
5V
Figure 17: SIM808 with battery charger and pack connection
4.4.1 Battery Pack Characteristics
SIM808 has optimized the charging algorithm for the Li-Ion battery that meets the characteristics listed below.
z The maximum charging voltage of the Li-Ion battery pack is 4.2V and the recommended capacity is
1100mAh. The Battery packs with more than 1100 mAh capacity will take more time for charging.
z The battery pack should have a protection circuit to avoid overcharging, deep discharging and over-current,
and the circuit should be insensitive to pulsed current.
z The internal resistance of the battery pack including protection circuit should be as low as possible. Its
recommended value does not exceed 150m.
z The battery pack must be protected from reverse pole connection.
On the SIM808, the build-in circuit of the power management chipset monitors the supply voltage constantly.
Once the Under-voltage is detected, the SIM808 will be powered down automatically.
4.4.2 Recommended Battery Pack
Following is the specification of recommended battery pack:
Table 9: Specification of recommended battery pack
Items Description
Battery type Li-ion
Manufacturer Jiade Energy Technology
Normal voltage 3.7V
Capacity NORMAL 1100mAh
Charge Voltage 4.200±0.050V
SIM808_Hardware Design_V1.00 2014.03.27
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