BQ2084DBTR-V150 Datasheet, PDF (21/69 Pages) Texas Instruments – SBS v1.1-COMPLIANT GAS GAUGE WITH LED DELAY

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bq2084-V150
SLUS758 – JUNE 2007
Table 9. Display Mode for Three LEDs (continued)
CONDITION
RELATIVE OR ABSOLUTE
StateOfCharge()
≤34%, < 67%
≤67%
THREE-LED DISPLAY OPTION
LED1
ON
ON
LED2
ON
ON
LED3
OFF
ON
LI-ION PROTECTION
The bq2084-V150 along with the bq29312A provides protection for Li-ion batteries, as shown in Table 10. The
bq2084-V150 measures temperature and current and uses the bq29312A to measure individual cell voltage. The
bq2084-V150 uses this information to determine protection requirements and control the safety FETs or SAFE
output as necessary. It is recommended that the bq2084-V150 protection control be validated by two successive
measurements by setting VOD=1 in Misc Configuration.
The bq29312A can independently detect and protect the load from an overload (OL) or short circuit in charge
(SCC) or discharge (SCD). The bq29312A sets the appropriate FET state and then alerts the bq2084-V150 with
the XALERT output whenever a protection threshold is breached and its associated delay time has expired. The
bq2084-V150 then determines if and when the FETs should be turned back on.
FLAG
CVOV
CVUV
Table 10. CVOV and CVUV Flags in PackStatus()
SET CONDITION
DSG FET CHG FET
CLEAR CONDITION⁽¹⁾
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-V150.
(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.
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