FS312F-G datasheet(8/13 Pages) FORTUNE

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11. Description of Operation

Normal Condition

If VODP<VCC<VOCP and VCH<VCS<VOI1, M1

and M2 are both turned on. The charging and

discharging processes can be operated normally.

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.

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.

Overcurrent Protection

In normal mode, the FS312F-G continuously

monitors the discharge current by sensing the

voltage of CS pin. If the voltage of CS pin exceeds

the overcurrent protection voltage (VOIP) beyond

the overcurrent delay time (TOI1) period, the

overcurrent

protection

circuit

operates

and

discharging is inhibited by turning off the discharge

control MOSFET. The overcurrent condition returns

to the normal mode when the load is released or the

impedance between BATT+ and BATT- is larger than

500kΩ. The FS312F-G provides two overcurrent

detection levels (0.15V and 1.35V) with two

overcurrent

delay

time

(TOI1

and

TOI2)

corresponding to each overcurrent detection level.

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 FS312F-G

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).

Power-Down after Overdischarge

When overdischarge occurs, the FS312F-G will

enter into power-down mode, turning off all the

timing generation and detection circuitry to reduce

the quiescent current to 0.1μ A (VCC=2.0V). At the

same time, the CS pin is pull-up to VCC through an

internal resistor.

Note: When a battery is connected to

FS312F-G for the first time, it may not enter the

normal condition (dischargeable may not be

enabled). In this case, short the CS and VSS

pins or connect to a charger to restore to the

normal condition.

FS312F-G データシート(PDF) 8 Page - Fortune Semiconductor Corp.

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