Datasheet

COV_FAULT
–
–
–
–
VC6 VC5 VC4
VC3
VC2 VC1
COVT Filter
Latch
VC6
LEVEL
SHIFTER
+
+
VSS
PROTECTOR
REFERENCE
CONFIG_COV[]
TRIP
SETPOINT
COV COMPARATOR
(one per cell)
STATUS
AR
FAULT
FAULT
ALERT
–
– –
ECC_
COR
UVLO
CBT DRDY
I_
FAULT
FORCE POR
CRC CUV
COV
FAULT_N
FAULT_S
FAULT_H
ANALOG TRANSLATION
IO_CONFIG[7]
bq76PL536A
SLUSAD3A –JUNE 2011–REVISED AUGUST 2012 www.ti.com
Cell Overvoltage Fault Detection (COV)
When the voltage across a cell exceeds the programmed COV threshold for a period of time greater than set in
the COV timer (COVT), the COV_FAULT[] flag for that cell is set. The bits in COV_FAULT[] are then ORed into
the FAULT[COV] flag, which is then ORed into the DEVICE_STATUS[FAULT] flag, which causes the FAULT_S
(_H) pin also to be asserted. The COV flag is latched unless COVT is programmed to 0, in which case the flag
follows the fault condition. Care should be taken when using this setting to avoid chatter of the fault status. To
reset the FAULT flag, first remove the source of the fault (i.e., the overvoltage condition) and then write a 1 to
FAULT[COV], followed by a 0 to FAULT[COV].
The voltage trip point is set in the CONFIG_COV register. Set points are spaced every 50 mV. Hysteresis is
provided to avoid chatter of the fault sensing. The filter delay time is set in the CONFIG_COVT[] register to
prevent false alarms. A start-up deglitch circuit is applied to the timers to prevent false triggering. The deglitch
time is 0–50 µs, and introduces a small error in the timing for short times. For both COVT and CUVT, this can
cause an error greater than the 10% maximum specified for delays <500 µs.
Figure 7. COV FAULT Simplified Logic Tree
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