BQ2084-V140_14 Datasheet, PDF (16/64 Pages) Texas Instruments – SBS v1.1-COMPLIANT GAS GAUGE FOR USE WITH THE bq29312

bq2084-V140
SLUS664B – JULY 2005 – REVISED AUGUST 2006
www.ti.com
Alarm Broadcasts to Smart Charger and Host
If any of the bits 8-15 in BatteryStatus() are set, the bq2084-V140 broadcasts an AlarmWarning() message to
the Host address. If any of the bits 12-15 in BatteryStatus() are set, the bq2084-V140 also sends an
AlarmWarning() message to the Smart Charger address. The bq2084-V140 repeats the AlarmWarning()
messages every 10 seconds until the alarm bits are cleared. All broadcasts can be disabled by setting SM (bit 2)
in Pack Configuration (DF 0x28).
Precharge Qualification
The bq2084-V140 sets ChargingCurrent() to the precharge rate as programmed in Precharge Current DF
0x42-0x43 under the following conditions:
• Voltage: The bq2084-V140 requests the precharge charge rate when any cell voltage drops below the
precharge threshold or when the EDV0 threshold is detected. Once requested, a precharge rate remains
until all cell voltages increase above the precharge threshold and the EDV0 condition does not exist. The
precharge threshold is programmed in Precharge Voltage DF 0x3c-0x3d.
• Temperature: The bq2084-V140 requests the precharge rate when Temperature() is between Charge Inhibit
Temp Low (DF0x46) and the precharge threshold programmed in Precharge Temp 0x44. Temperature( )
must be equal to or greater than the precharge threshold + 3°C to allow the fast-charge rate.
Charge Suspension
The bq2084-V140 may temporarily suspend charge if it detects a charging fault. A charging fault includes the
following conditions.
• Overcurrent: An overcurrent condition exists when the bq2084-V140 measures the charge current to be
greater than Charge OC Threshold (DF 0x12a-0x12b) for a time greater than Charge OC Time (DF 0x12c).
On detecting an overcurrent condition, the bq2084-V140 turns off the Charge FET. If the Nonremovable
Battery bit is not set in Misc Configuration DF 0x2a, then the Discharge FET is turned off also. This condition
is cleared when the pack is removed or if the Nonremovable Battery bit is set in Misc Configuration DF 0x2a
and when a discharge current is detected or when SBS AverageCurrent() is less than the ClearFailCurrent
DF 0x61-0x62 for FaultResetTime DF 0x130.
• Overtemperature: During charging, an overtemperature condition exists when Temperature() is greater than
the Charge Suspend Temp High value programmed in DF 0x6d, 0x6e. On detecting an overtemperature
condition, if enabled by the OT bit in Misc Configuration DF 0x2a, the bq2084-V140 turns off the Charge and
Discharge FETs. The overtemperature condition is cleared when Temperature() is equal to or below Charge
Suspend Temp High Reset (DF 0x6f -0x70). The condition is also cleared if the pack is removed.
• Undertemperature: During charging, an undertemperature condition exists when Temperature() is less than
the Charge Suspend Temp Low in DF 0x79 or Charge Inhibit Temp Low in DF 0x46. On detecting an
undertemperature condition the bq2084-V140 turns off the Charge FET. The undertemperature condition is
cleared when Temperature() is greater than Charge Suspend Temp Low DF 0x79. The condition is also
cleared if the pack is removed. The maximal value of Charge Suspend Temp Low setting is 12.7°C.
• Charging exceeds Maximum Charging Time in DF 0x10f-0x110. If charging time reaches Maximum Charge
Time, the Charge FET is turned off. This condition is cleared when the pack detects discharge current or is
removed.
• Cell or Pack Overvoltage: An overvoltage condition exist when any cell is greater than Cell Over Voltage
Limit in DF 0x63-0x64 or if Voltage() is greater than Charging Voltage in 0x3a-0x3b plus OvervoltageMargin
in 0x5d-05e. This condition is cleared when the pack is removed or if the Nonremovable Battery bit is set in
Misc Configuration DF 0x2a and when a discharge current is detected or when SBS AverageCurrent() is
less than the ClearFailCurrent DF 0x61-0x62 for FaultResetTime DF 0x130. Also, the overvoltage condition
must be cleared by Voltage() less than Charging Voltage in 0x3a-0x3b plus OvervoltageMargin in 0x5d-05e
and all cell voltages less than Cell Over Voltage Reset in DF 0xe0-0xe1.
• Charging is also temporarily suspended during pulse-charging, but this is not considered a fault condition.
Pulse Charge
The bq2084-V140 is capable of charge control using a pulse-charging algorithm, which allows for charge control
in systems where the charger does not control current.
The pulse-charging algorithm uses voltage thresholds and associated time limits for control. These are stored as
constants in data flash. The cell voltages are read by the a/d converter every 125 ms during charging. The
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