3.1 Introduction
The device can permanently disable the battery pack in the case of a severe failure, such as an error in the
instruction flash check (IFC) or in the data flash write (DFW). An IFC failure is set by the gauge if the signature
fails to pass verification at power-on reset. The DFW failure is set by the gauge if it is unable to successfully
program an update to the data flash (the read-back verification fails). When one of these failure modes is
detected, the following actions are taken in sequence:
1. Charge and discharge FETs are turned off.
2.
OperationStatus()[PF]
= 1
3. The following data is changed:
BatteryStatus()[TCA]
= 1,
BatteryStatus()[TDA]
= 1,
ChargingCurrent()
= 0,
and
ChargingVoltage()
= 0.
4. A backup of the internal AFE hardware registers are written to data flash:
AFE Interrupt Status
,
AFE
FET Status
,
AFE RXIN
,
AFE Latch Status
,
AFE Interrupt Enable
,
AFE FET Control
,
AFE RXIEN
,
AFE
Cell Balance
,
AFE AD/CC Control
,
AFE ADC Mux
,
AFE State Control
,
Wake Control
,
AFE Protection
Control
,
AFE OCD
,
AFE SCC
,
AFE SCD1
, and
AFE SCD2
.
5. The following values are preserved in data flash for failure analysis:
•
SafetyAlert()
•
SafetyStatus()
•
OperationStatus()
•
ChargingStatus()
•
GaugingStatus()
• Voltages in
DAStatus1()
•
Current()
• TSINT, TS1, from
DAStatus2()
• Cell DOD0 and passed charge
6. Data flash writing is disabled.
While the device is in this PERMANENT FAIL mode, any new
SafetyAlert()
,
SafetyStatus()
flags that are set are
added to the permanent fail log.
3.2 Safety Cell Overvoltage Permanent Fail
The device can permanently disable the battery in the case of severe overvoltage in any of the cells.
Status
Condition
Action
Normal
All Cell voltages in
DAStatus1()
<
SOV:Threshold
PFAlert()[SOV]
= 0
Alert
Any Cell voltages in
DAStatus1()
≥
SOV:Threshold
PFAlert()[SOV]
= 1
BatteryStatus()[TCA]
= 1
BatteryStatus()[OCA]
= 1
Trip
Any Cell voltages in
DAStatus1()
continuous ≥
SOV:Threshold
for
SOV:Delay
duration
PFAlert()[SOV]
= 0
PFStatus()[SOV]
= 1
BatteryStatus()[OCA]
= 1
BatteryStatus()[TCA]
= 1
BatteryStatus()[TDA]
= 1
Chapter 3
Permanent Fail
Permanent Fail
SLUUCO0 – APRIL 2022
BQ28Z610-R2
19
Copyright © 2022 Texas Instruments Incorporated
