BQ2084-V140_14 Datasheet, PDF (20/64 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
The bq29312 can independently detect and protect the load from an overload (OL) or short circuit in charge
(SCC) or discharge (SCD). The bq29312 sets the appropriate FET state and then alerts the bq2084-V140 with
the XALERT output whenever a protection threshold is breached and its associated delay time has expired. The
bq2084-V140 then determines if and when the FETs should be turned back on.
Table 10. CVOV and CVUV Flags in PackStatus()
FLAG
SET CONDITION
DSG FET CHG FET
CLEAR CONDITION⁽¹⁾
CVOV
CVUV
Voltage() = ChargingVoltage() + Over
Voltage Margin
VCELL_(ANY) = Cell Over Voltage
VCELL_(ANY) = Cell Under Voltage
AverageCurrent() < - Over Load Current
ON
ON
OFF ⁽³⁾
OFF ⁽²⁾
OFF ⁽²⁾
(3)_ON
ON
Voltage() < ChargingVoltage()
VCELL_(ALL) < Cell Over Voltage Reset
VCELL_(ALL) > Cell Under Voltage Reset
AverageCurrent() < - Current Fault Clear Threshold
(1) Clear is detected and controlled by the bq2084-V140.
(2) On if there is a discharge current ≤150 mA
(3) On if there is a charge current ≤50 mA
Protection Configuration
1^st Level Cell Voltage Thresholds
The cell undervoltage (VUV) and overvoltage (VOV) limits are programmed in Cell Under Voltage and Cell Over
Voltage DF 0x65-0x66, DF 0x63-0x64, respectively. Both values are stored in mV. Cell Over Voltage Reset DF
0xe0-0xe1 and Cell Under Voltage Reset 0xe2-0xe3 set the reset points in mV for these safety parameters.
Safety Overvoltage Threshold
The safety voltage threshold is programmed in Safety Over Voltage DF 0x6b-0x6c. It is stored in mV. Exceeding
the Safety Voltage for a period determined by the MISC Config VOD bit causes permanent failure if enabled by
PFConfig.
Overcurrent Thresholds
Discharge current threshold is programmed in Discharge OC Threshold DF 0x12d-0x12e. The discharge
overcurrent must exist for time programmed in Discharge OC Time DF 0x12f. When a discharge overcurrent
condition is detected the discharge FET is turned off. Similarly, a charge overcurrent is programmed in Charge
OC ThresholdDF 0x12a-0x12b. The charge overcurrent must exist for the time programmed in Charge OC Time
DF 0x12c or Charge OC Time DF 0x12c. When a charge overcurrent condition is detected, the charge FET is
turned off.
Temperature Thresholds
The Safety Over Temperature in Charge (SOTC) threshold is programmed in Safety Over Temperature in
Charge DF 0x75-0x76 and Safety Over Temperature in Discharge (SOTD) threshold is programmed in Safety
Over Temperature in Discharge DF 0x77-0x78.
SOTC is stored as Safety Over Temperature in Charge = SOTC/0.1 (°C) as an unsigned integer
SOTD is stored as Safety Over Temperature in Discharge = SOTD/0.1 (°C) as an unsigned integer. Exceeding
the Safety Temperatures for a period exceeding Over Temperature Time DF 0x162 causes permanent failure if
enabled by PFConfig.
There are also temperature thresholds to disable both charge and discharge FETs and to set the SBS Battery
Status Overtemperature bit. The thresholds are set according to whether discharge or charge is detected. The
Charge Suspend Temp High threshold is stored in DF 0x6d-0x6e with the reset threshold stored in DF
0x6f-0x70. Likewise, the Over Temperature Discharge threshold is stored in DF 0x71-0x72 with the reset
threshold stored in DF 0x73-0x74. If the OT bit in Misc Configuration is set then all temperature protection is
disabled except for Safety Over Temperature.
The Charge Suspend Temp Low threshold (CSTL) is stored in Charge Suspend Temp Low DF 0x79-0x7a and is
stored as Charge Suspend Temp Low = CSTL/0.1 (°C) as a signed integer. A Charge Suspend Temp Low turns
off the charge FET. The maximal value of Charge Suspend Temp Low setting is 12.7 °C.
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