BQ2084DBTR-V150 Datasheet, PDF (23/69 Pages) Texas Instruments – SBS v1.1-COMPLIANT GAS GAUGE WITH LED DELAY

bq2084-V150
www.ti.com
SLUS758 – JUNE 2007
The AFE protection features can also recover automatically after AFE Recovery Time (DF 0x160) if the AFE
Recovery Time is set to a nonzero value. When the protection feature is recovered in this manner, it does not
re-trigger for AFE Hold Off Time (DF 0x161).
AFE Integrity Check
The bq2084-V150 checks the programming of the AFE registers at a period determined by AFE Check Time DF
0xfb. The units of the check period are seconds unless the bq2084-V150 is in sleep mode, in which case the
period is AFE Check Time x Sleep Current Multiplier (DF 0xfd). If the data is not correct, the bq2084-V150
increments an internal counter until it reaches the AFE Fail Limit (DF 0xe4). Setting AFE Check Time to 0
disables this function.
When the internal AFE Fail counter reaches AFE Fail Limit, then the AFE bit in PF Status is set.
AFE Watchdog Fault and Clear
The bq29312A has a feature where the 32-kHz output (CLKOUT, pin 35) of the bq2084-V150 is used to drive its
internal clock. If this clock fails, a fault is declared in the AFE. See the bq29312A data sheet for further details.
The fault is cleared automatically on return of the 32-kHz input via the bq2084-V150 CLKOUT pin.
Permanent Failure Mode (SAFE Output)
The SAFE output of the bq2084-V150 provides an additional level of safety control. The active low safety output
can blow a fuse or control another switch on the basis of temperature, pack-voltage cell-voltage, CHG FET
Failure, severe cell imbalance, or an integrity check of the AFE and Data Flash configuration registers.
The bq2084-V150 can also activate the SAFE output and set the PF Flag based on the PFIN input. If this pin is
low for PFIN Time seconds ±1 s, then the PFIN bit in PF Status is set.
The SAFE output can be driven low in any of the following conditions, and the bq2084-V150 sets the PF Flag
register (DF 0x11e) to 0x66 (011001100). The activation of the SAFE output and the setting of the PF Flag can
be enabled or disabled for different safety option per the PF Config (DF 0x11f) register settings.
The SAFE output and PF Flag register can only be cleared using a series of ManufacturerAccess() commands.
Table 12. SAFE Activation Conditions⁽¹⁾
CONDITION
Voltage() > Safety Over Voltage (DF 0x6b and 0x6c),
Temperature() > Safety Over Temperature in Charge (DF 0x75 and 0x76)
Temperature() > Safety Over Temperature in Discharge (DF 0x77 and 0x78)
When Miscellaneous Configuration (0x2a) bit 13 AC is set, and the number of AFE failures has reached the AFE Fail
Limit (DF 0xe4)
When VCELL_(MAX) - VCELL_(MIN) > Cell Imbalance Threshold (DF 0xee, 0xef) during charging
If charge FET is off, and charge current greater than FET Fail charge current stored in DF 0x125-0x126 for the time
determined by FET Fail time in DF 0x129, or if discharge FET is off and discharge current greater than FET Fail
discharge current stored in DF 0x127-0x128 for the time determined by FET Fail time in DF 0x129.
The PFIN input has detected a low state for PFIN Time in consecutive seconds, as determined by DF 0x120
(1) SAFE output activated and PF Flag set only if enabled by PF Config (DF 0x0x11f)
ACTIONS
SOV and PF set
SOTC and PF set
SOTD and PF set
AFE and PF set
CIM and PF set
FETF and PF set
PFIN, PF set
Permanent Failure Status (PF Status)
PF Status DF 0x11d contains the flags for the cause of the permanent failure mode.
b7
b6
b5
b4
PFF
PFIN
FETF
CIM
b3
b2
b1
b0
AFE
SOTD
SOTC
SOV
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