BQ2085-V1P3 Datasheet, PDF (14/57 Pages) Texas Instruments – SBS-COMPLIANT GAS GAUGE IC FOR USE WITH THE bq29311

bq2085-V1P3
SLUS598 − FEBRUARY 2004
www.ti.com
Charge Control
Charging Voltage and Current Broadcasts
The bq2085−V1P3 supports SBS charge control by broadcasting the ChargingCurrent( ) and
ChargingVoltage( ) to the Smart Charger address. The bq2085−V1P3 broadcasts the requests every 50
seconds. The bq2085−V1P3 updates the values used in the charging current and voltage broadcasts based
on the battery’s state of charge, voltage, and temperature. The charge voltage is programmed in Charging
Voltage DF 0x039-0x3a. The charge current may take any of four different values: Fast Charging Current DF
(0x3d–0x3c), Maintenance Charging Current (DF 0x3f), Precharge Current (0x41), or 0. The charge current
depends on charge state and operating conditions.
The bq2085−V1P3 internal charge control is compatible with the constant current/constant voltage profile for
Li-Ion. The bq2085−V1P3 detects primary charge termination on the basis of the tapering charge current during
the constant-voltage phase.
Alarm Broadcasts to Smart Charger and Host
If any of the bits 8−15 in BatteryStatus( ) are set, the bq2085−V1P3 broadcasts an AlarmWarning( ) message
to the Host address. If any of the bits 12−15 in BatteryStatus( ) are set, the bq2085−V1P3 also sends an
AlarmWarning( ) message to the Smart Charger address. The bq2085−V1P3 repeats the AlarmWarning( )
messages every 10 seconds until the alarm bits are cleared.
Precharge Qualification
The bq2085−V1P3 sets ChargingCurrent( ) to the precharge rate as programmed in Precharge Current DF
0x41 under the following conditions:
D Voltage: The bq2085−V1P3 requests the precharge charge rate when Voltage( ) drops below the precharge
threshold or when the EDV0 threshold is detected. Once requested, a precharge rate remains until Voltage( )
increases above the precharge threshold and the EDV0 condition does not exist. The precharge threshold is
programmed in Precharge Voltage DF 0x3b−0x3c.
D Temperature: The bq2085−V1P3 requests the precharge rate when Temperature( ) is between 0°C and the
precharge threshold programmed in Precharge Temp 0x43. Temperature( ) must be equal to or greater than the
precharge threshold to allow the fast-charge rate.
Charge Suspension
The bq2085−V1P3 may temporarily suspend charge if it detects a charging fault. A charging fault includes the
following conditions.
D Overcurrent: An overcurrent condition exists when the bq2085−V1P3 measures the charge current to be equal
to or greater than Overcurrent Margin plus ChargingCurrent( ). Overcurrent Margin is programmed in DF
0x5c−0x5d. On detecting an overcurrent condition, the bq2085−V1P3 sets the ChargingCurrent( ) to zero and
sets the TERMINATE_CHARGE_ALARM bit in Battery Status( ). The overcurrent condition and TERMINATE_
CHARGE_ALARM are cleared when the measured current drops below Overcurrent Margin.
D Overvoltage: An overvoltage condition exists when the bq2085−V1P3 measures the battery voltage to be more
than Over Voltage Margin plus ChargingVoltage( ), or when a cell voltage has exceeded the overvoltage limit
programmed in Cell Over Voltage. Over Voltage Margin is programmed in DF 0x5a−0x5b and Cell Over Voltage
in DF 0x60. On detecting an overvoltage condition, the bq2085−V1P3 sets the ChargingCurrent( ) to zero and
sets the TERMINATE_CHARGE_ALARM bit in BatteryStatus( ). The bq2085−V1P3 clears the TERMINATE_
CHARGE_ALARM bit when it detects that the battery is no longer being charged (DISCHARGING bit set in
BatteryStatus( )). The bq2085−V1P3 continues to broadcast zero charging current until the overvoltage
condition is cleared. The overvoltage condition is cleared when the measured battery voltage drops below the
ChargingVoltage( ) plus the Over Voltage Margin and all cell voltages are less than the Cell Over Voltage Reset
threshold in DF 0xcf, 0xd0.
D Overtemperature: An overtemperature condition exists when Temperature( ) is greater than or equal to the Max
Temperature value programmed in DF 0x53, 0x54. On detecting an overtemperature condition, the
bq2085−V1P3 sets the ChargingCurrent( ) to zero and sets the OVER_TEMP_ALARM and
TERMINATE_CHARGE_ ALARM bit in BatteryStatus( ) and the CVOV bit in pack status. The overtemperature
condition is cleared when Temperature( ) is equal to or below (Max Temperature − Temperature Hysteresis DF
0x55, 0x56) or 43°C.
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