BQ2084-V140_14 Datasheet, PDF (15/64 Pages) Texas Instruments – SBS v1.1-COMPLIANT GAS GAUGE FOR USE WITH THE bq29312

bq2084-V140
www.ti.com
Voltage()
SLUS664B – JULY 2005 – REVISED AUGUST 2006
Table 5. Midrange Corrections
CONDITION
≤ VOC75 and RelativeStateOfCharge() ≤ 63%
≤ VOC75 and RelativeStateOfCharge() ≤ 87%
≤ VOC50 and RelativeStateOfCharge() <38%
<VOC50 and RelativeStateOfCharge() ≤ 62%
≤ VOC25 and RelativeStateOfCharge() ≤ 13%
< VOC25 and RelativeStateOfCharge() ≤ 37%
RESULT
RelativeStateOfCharge() → 75%
RelativeStateOfCharge() → 75%
RelativeStateOfCharge() → 50%
RelativeStateOfCharge() → 50%
RelativeStateOfCharge() → 25%
RelativeStateOfCharge() → 25%
Three voltage-based thresholds, VOC25 DF 0x88-0x89, VOC50 DF 0x83-0x84, and VOC75 DF 0x7e-0x7f, are
stored in the data flash in mV.
Charge Control
The bq2084-V140 internal charge control is compatible with the constant current/constant voltage profile for
Li-ion. The bq2084-V140 detects primary charge termination on the basis of the tapering charge current during
the constant-voltage phase.
Charging Voltage Broadcasts
The bq2084-V140 supports SBS charge control by broadcasting the ChargingCurrent() and ChargingVoltage() to
the Smart Charger address. The bq2084-V140 broadcasts the requests every 10 seconds. The bq2084-V140
updates the values used in the charging current and voltage broadcasts based on the battery's state of charge,
voltage, and temperature.
The 16-bit value (mV) for charging voltage is programmed in Charging Voltage DF 0x03a-0x3b although it can
be set to 0 in different operating conditions. It also sets the base value for determining overvoltage conditions
during charging and voltage compliance during a constant-voltage charging methodology.
The 16-bit value, Over Voltage Margin DF 0x5d-0x5e, sets the limit over ChargingVoltage() in mV that is to be
considered as an overvoltage charge-suspension condition.
Charging Current Broadcasts
ChargingCurrent() values are either broadcast to a Level 2 smart battery charger or read from the bq2084-V140
by a Level 3 smart battery charger. The ChargingCurrent() may take any of four different values: Fast-Charging
Current DF (0x3e-0x3f), Maintenance Charging Current (DF 0x40-0x41), Precharge Current (0x42-0x43) or 0
depending on charge state and operating conditions.
When fast charge is allowed, the bq2084-V140 sets ChargingCurrent() to the rate programmed in Fast-Charging
Current DF 0x3e-0x3f. Fast-Charging Current is stored in mA.
When fast charge terminates, the bq2084-V140 sets ChargingCurrent() to zero and then to the
MaintenanceCharging Current DF 40 0x41 when the termination condition ceases. The desired maintenance
current is stored in mA.
When Voltage() is less than EDV0, the bq2084-V140 sets ChargingCurrent() to Precharge Current DF 0x42,
0x43. Typically this rate is larger than the maintenance rate to charge a deeply depleted pack up to the point
where it may be fast charged. The desired precharge rate is stored in mA.
If temperature is between the Charge Inhibit Temp Low (DF0x46) and the precharge threshold PC (°C), the
bq2084-V140 sets ChargingCurrent() to Precharge Current. The threshold is programmed in the Precharge
Temp DF 0x44. The maximal value of precharge temperature threshold setting is 12.7°C.
• Precharge Temp = PC (°C) / 0.1
The bq2084-V140 also sets ChargingCurrent() to the precharge rate if Voltage() is less than the value
programmed in Precharge Voltage DF 0x3c-0x3d. Precharge Voltage is programmed in mV.
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