fs326 Fortune Semiconductor Corporation, fs326 Datasheet - Page 10

• Manufacturer Part Number: fs326
• Description: One Cell Lithium-ion/polymer Battery Protection Ic
• Manufacturer: Fortune Semiconductor Corporation

Rev. 1.9
12. Description of Operation
12.1
12.2
12.3
12.4
12.5
Normal Condition
Overcharge Condition
Release of Overcharge Condition
Overdischarge Condition
Release of Power-down mode
Note: When a battery is connected to FS326 for the first time, it may not enter the normal
The FS326 monitors the voltage of the battery connected between VDD and VSS. The charge
and discharge scheme will be sensed by the voltage difference between CSI and VSS. When
VODL<VDD<VOCU and VCH<VCSI<VOI1, FS326 will turn on the charging (M2) and discharging
(M1) control MOSFETs. The charging and discharging processes can be operated normally. This
is called the normal condition.
When the battery voltage becomes higher than the overcharge detection voltage (VOCU) during
normal charging condition through a delay time longer than TOC (the overcharge detection delay
time), FS326 will turn M2 off to stop charging. This condition is called the overcharge condition.
There are two ways to return to normal condition from overcharge condition.
1)
2)
Note 1: After entering the overcharge condition, if the charger remains connected and
Note 2: After entering the overcharge condition, if the charger remains connected and
When the battery voltage falls below the overdischarge detection voltage (VODL) during
discharging condition and through a delay time longer than TOD (the overdischarge detection
delay time), FS326 will turn M1 off to stop discharging. This is called the overdischarge condition.
In the meanwhile, CSI will be pulled up to VDD through an internal resistance. If VCSI>VOI2,
FS326 will enter into power-down mode. While in this mode, the current consumption is lower
than 0.1 μ A.
After entering power-down mode, when the system is connected to a charger, the charging
current will flow through the parasitic diode of M1. If VCSI<VOI2 occurs, then FS326 will release
power-down mode. While keeping charging status, there are two ways back to normal condition:
1)
When the battery is self discharging, and if VDD<VOCR and VOI1>VCSI>VCH occurs, M2
will be
Remove the charger and connect FS326 to a load, the discharging current will flow through
the parasitic diode of M2. At this moment, VCSI increases a voltage (VF) of the parasitic
diode from the VSS level momentarily. While VCSI>VOI1 and VDD<VOCU occurs, M2 will
be turned on and back to normal condition.
If VCSI<VCH (Charger detection), then when VDD>VODL, M1 will be turned on and the
system will back to normal condition.
condition (dischargeable may not be enabled). In this case, short the CSI and VSS pins or
connect a charger to restore to the normal condition.
VOI1>VCSI>VCH, then M2 will be turned on when the voltage of the battery is lower
than VOCR (because the self-discharge of the battery). The system can enter the
charging status again as 1) .
VCSI<VCH, then M2 will be kept off even though the voltage of the battery is lower than
VOCR (because the self-discharge of the battery), and the system will not be allowed to
enter the charging status.
turned on and back to normal condition.
FS326
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