fs3332 Fortune Semiconductor Corporation, fs3332 Datasheet - Page 14

• Manufacturer Part Number: fs3332
• Description: Two Cell Lithium-ion/polymer Battery Protection Ic
• Manufacturer: Fortune Semiconductor Corporation

Rev. 1.0
When one of the battery voltages falls below over-discharge detection voltage (VDL1,2) during discharging in
12. Description of Operation
12.1 Normal Condition
This IC monitors the voltage of the battery connected between the VDD and VSS pins and the voltage
difference between the VM and VSS pins to control charging and discharging. When the voltages of two
batteries are in the range from over-discharge detection voltage (VDL1,2) to overcharge detection voltage
(VCU1,2), and the VM pin voltage is in the range from the charger detection voltage (VCHA) to over-current
detection voltage 1 (VIOV1), the IC turns both the charging and discharging control FETs on. This condition is
called the normal status, and in this condition charging and discharging can be carried out freely. The VM and
VSS pins are shorted by the RVSM resistor in this condition.
Caution: When the battery is connected for the first time, discharging may not be enabled. In this case, short
the VM and VSS pins or connect the charger to restore the normal status.
12.2 Overcharge Condition
When one of the battery voltages becomes higher than overcharge detection voltage (VCU1,2) during charging
in the normal status and detection continues for the overcharge detection delay time (tCU1,2) or longer, the
charging control FET turns off to stop charging. When one of the battery voltages becomes higher than
auxiliary overcharge detection voltage (VCUAUX1,2), the charging control FET turns off to stop charging, too.
Both conditions are called the overcharge status. The VM and VSS pins are shorted by the RVSM resistor in
this condition.
12.3 Over-discharge Condition
the normal status and detection continues for the over-discharge detection delay time (tDL1,2) or longer, the
discharging control FET turns off to stop discharging. This condition is called the over-discharge status. When
the discharging control FET is turned off, the VM pin voltage is pulled up by the resistor between the VM and
VDD pins in the IC (RVMD). When the voltage difference between the VM and VDD pins then is over-current
detection voltage 2 or lower, the current consumption is reduced to the power-down current consumption
(IPDN). This condition is called the power-down status. The power-down status is released when a charger is
connected and the voltage difference between the VM and VDD pins is over-current detection voltage 2 or
higher. Moreover, when all the battery voltages become over-discharge detection voltage (VDL1,2) or higher,
the discharging FET turns on and returns to the normal status.
The overcharge status is released in the following two cases (a and b).
a) The battery voltage which exceeded overcharge detection voltage (VCU1,2) falls below the overcharge
release voltage (VCR1,2), the charging control FET turns on and returns to the normal status.
b) The battery voltage which exceeded overcharge detection voltage (VCU1,2) is equal to or higher than
the overcharge release voltage (VCR1,2), the charger is removed, a load is connected and discharging
starts, the charging control FET turns on and returns to the normal status. Just after the load is connected
and discharging starts, the discharging current flows through the parasitic diode in the charging control
FET. At this moment the VM pin potential becomes Vf, the voltage for the parasitic diode, higher than the
VSS level. When the battery voltage goes under overcharge detection voltage (VCU1,2) and provided
that the VM pin voltage is higher than over-current detection voltage 1, the IC releases the overcharge
status and returns to the normal status.
FS3332
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