FS8820P datasheet(8/13 Pages) FORTUNE

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FS8820P

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 FS8820P 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

FS8820P 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 FS8820P

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).

Auto Power Down recovery

The IC continues to operate even after the

overdischarge state has been entered. The

battery voltage rising to the overdischarge

release voltage(VODR) or higher is the only

required condition for the IC to return to the

normal state.

Rev. 1.8

8/13

FS8820P Datasheet(PDF) 8 Page - Fortune Semiconductor Corp.

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