fs361b Fortune Semiconductor Corporation, fs361b Datasheet - Page 8

• Manufacturer Part Number: fs361b
• Description: One Cell Lithium-ion/polymer Battery Protection Ic
• Manufacturer: Fortune Semiconductor Corporation

FS361
11. Description of Operation
11.1 Overcharge Protection
When the voltage of the battery cell exceeds the overcharge protection voltage (VOCP) beyond the overcharge
delay time (TOC) period, charging is inhibited by turning off of the charge control MOSFET. The overcharge
condition is released in two cases:
The voltage of the battery cell becomes lower than the overcharge release voltage (VOCR) through
self-discharge.
The voltage of the battery cell falls below the overcharge protection voltage (VOCP) and a load is connected.
When the battery voltage is above VOCP, the overcharge condition will not release even a load is connected to
the pack.
11.2 Overdischarge Protection
When the voltage of the battery cell goes below the overdischarge protection voltage (VODP) beyond the
overdischarge delay time (TOD) period, discharging is inhibited by turning off the discharge control MOSFET.
The default of overdischarge delay time is 10ms. Inhibition of discharging is immediately released when the
voltage of the battery cell becomes higher than overdischarge release voltage (VODR) through charging.
11.3 Short current Protection
In normal mode, the FS361 continuously monitors the discharge current by sensing the voltage of CS pin. If the
voltage of CS pin exceeds the short current protection voltage (VOI2) beyond the short current delay time
(TOI2) period, the short current protection circuit operates and discharging is inhibited by turning off the
discharge control MOSFET. The short current condition returns to the normal mode when the load is released
or the impedance between BATT+ and BATT- is larger than 500kΩ. The FS361 provides short current detection
levels (1.35V) with delay time (TOI2).
11.4 Charge Detection after Overdischarge
When overdischarge occurs, the discharge control MOSFET turns off and discharging is inhibited. However,
charging is still permitted through the parasitic diode of MOSFET. Once the charger is connected to the battery
pack, the FS361 immediately turns on all the timing generation and detection circuitry. Charging progress is
sensed if the voltage between CS and GND is below charge detection threshold voltage (VCH).
11.5 Power-Down after Overdischarge
When overdischarge occurs, the FS361 will enter into power-down mode, turning off all the timing generation
and detection circuitry to reduce the quiescent current to 0.1μA (VCC=2.0V). At the same time, the CS pin is
pull-up to VCC through an internal resistor.
Rev. 1.0
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