BQ2085 Datasheet, PDF (16/56 Pages) Texas Instruments – SBS-COMPLIANT GAS GAUGE IC FOR USE WITH THE bq29311

bq2085
SLUS541 – OCTOBER 2002
TERMINATE_CHARGE_ALARM when it no longer detects that the battery is being charged or it no longer
detects the termination condition. See Table 6 for a summary of BatteryStatus( ) alarm and status bit
operation.
Table 6. Alarm and Status Bit Summary
BATTERY STATE
CONDITIONS
CC( ) CURRENT AND
STATUS BITS SET
STATUS CLEAR CONDITION
Overcurrent
C( ) ≥ CC( ) + Overcurrent Margin
CC( ) = 0, TCA = 1
C( ) < Overcurrent Margin
Prolonged
Overcurrent
AC( ) ≥ Fast-Charging Current +
Overcurrent Margin
CVOV = 1
CC( ) = 0, TCA = 1
AC( ) < 256 mA
Overload
AC( ) ≤ –Overload Current
CVUV = 1
AC( ) < –256 mA
Overvoltage
V( ) ≥ CV( ) + Over Voltage Margin
VCELL1, 2, 3, or 4 ≥ Cell Over Voltage
TCA = 1
CC( ) = 0, CVOV = 1
DISCHARGING = 1
V( ) < CV( ) + Over Voltage Margin
VCELL(all) ≤ Cell Over Voltage Reset
Overtemperature T( ) ≥ Max Temperature
CC( ) = 0, OTA = 1,
TCA = 1, CVOV = 1
T( ) ≤ Max Temperature –Temperature
Hysteresis or T( ) ≤ 43°C
Overcharge
Capacity added after RM( ) = FCC( ) ≥
Maximum Overcharge
CC( ) = 0, FC = 1
OCA = 1, TCA = 1
RSOC( )< Fully Charged Clear %
DISCHARGING = 1, and 2 mAh of
discharge is measured
T( ) < 0°C
Undertemperature
0°C ≤ T( ) < LTF
CC( ) = 0
CC( ) = Precharge
0°C ≤ T( )
T( ) ≥ LTF + DF 0x44 (default = 3°C)
Primary Charge
Termination
Current taper
FC = 1, TCA = 1
CC( ) = Maintenance
Charging Current
RSOC( ) < Fully Charged Clear%
Fully Discharged
RM( ) < Battery Low % and
DISCHARGING = 1
FD = 1
RSOC( ) ≥ 20%
Overdischarged
RM( ) = 0
V( ) ≤ Terminate Voltage
VCELL1, 2, 3 or 4 ≤ Cell Under Voltage
TDA = 1
TDA = 1, CVUV = 1
V( ) > Terminate Voltage and RM( ) > 0
V( ) > Terminate Voltage
VCELL(all) ≥ Cell Under Voltage Reset
Low Capacity
RM( ) < RCA( )
RCA = 1
RM( ) ≥ RCA( )
Low Run Time
ATTE( ) < RTA( )
RTA = 1
ATTE( ) ≥ RTA( )
NOTE: AC( ) = AverageCurrent( ), C( ) = Current( ), CV( ) = ChargingVoltage( ), CC( ) = ChargingCurrent( ), V( ) = Voltage( ),
T( ) = Temperature( ), TCA = TERMINATE_CHARGE_ALARM, OTA = OVER_TEMPERATURE_ALARM,
OCA = OVER_CHARGED_ALARM, TDA = TERMINATE_DISCHARGE_ALARM, FC = FULLY_CHARGED,
FD = FULLY_DISCHARGED, RSOC( ) = RelativeStateOfCharge( ). RM( ) = RemainingCapacity( ),
RCA = REMAINING_CAPACITY_ALARM, RTA = REMAINING_TIME_ALARM, ATTE( ) = AverageTimeToEmpty( ),
RTA( ) = RemainingTimeAlarm( ), RCA( ) = RemainingCapacityAlarm( ). LTF = Low Temperature Fault threshold
FCC( ) = Full Charge Capacity
Cell Balancing
The bq2085 balances the cells during charge by discharging those cells above the threshold set in Cell Balance
Threshold DF 0xd7–0xd8, if the maximum difference in cell voltages exceeds the value programmed in Cell
Balance Min DF 0xdb. For cell balancing, the bq2085 measures the cell voltages at an interval set in Cell
Balance Interval DF 0xdc. On the basis of the cell voltages, the bq2085 either selects the appropriate cell to
discharge or adjusts the cell balance threshold up by the value programmed in Cell Balance Window 0xd9–0xda
when all cells exceed the cell balance threshold or the highest cell exceeds the cell balance threshold by the
cell balance window.
The cell balance threshold is reset to the value in Cell Balance Threshold at the start of every charge cycle. The
threshold can be adjusted no more than once during a balance interval.
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