BQ2084DBTR-V150 Datasheet, PDF (16/69 Pages) Texas Instruments – SBS v1.1-COMPLIANT GAS GAUGE WITH LED DELAY

bq2084-V150
SLUS758 – JUNE 2007
www.ti.com
For the midrange corrections to occur, the temperature must be in the range of 19°C to 31°C inclusive and
Current() and AverageCurrent() must both report between -64 mA and 0. The bq2084-V150 makes midrange
corrections as shown in Table 5. For a correction to occur, the bq2084-V150 must detect the need for correction
twice during subsequent 20-s intervals. With the VCOR bit set, the bq2084-V150 makes midrange corrections
whenever conditions permit.
If the OTVC bit in Gauge Configuration DF 0x29 is set and VCOR = 0, the bq2084-V150 makes two Voltage()
measurements, determines the average of the two readings and sets the appropriate RM level. No further
RSOC% vs Voltage() validation is performed until after the next device reset.
Voltage()
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-V150 internal charge control is compatible with the constant current/constant voltage profile for
Li-ion. The bq2084-V150 detects primary charge termination on the basis of the tapering charge current during
the constant-voltage phase.
Charging Voltage Broadcasts
The bq2084-V150 supports SBS charge control by broadcasting the ChargingCurrent() and ChargingVoltage() to
the Smart Charger address. The bq2084-V150 broadcasts the requests every 10 seconds. The bq2084-V150
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-V150
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-V150 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-V150 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-V150 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.
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