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SLUUBD3D–September 2015–Revised September 2018
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Copyright © 2015–2018, Texas Instruments Incorporated
Permanent Fail
Chapter 4
SLUUBD3D–September 2015–Revised September 2018
Permanent Fail
4.1 Introduction
The device can permanently disable the use of the battery pack in case of a severe failure. The
permanent failure checks, except for IFC and DFW, can be individually enabled or disabled by setting the
appropriate bit in Settings:Enabled PF A, Settings:Enabled PF B, Settings:Enabled PF C, and
Settings:Enabled PF D. All permanent failure checks except for IFC and DFW are disabled until
ManufacturingStatus()[PF] is set. When any PFStatus() bit is set, the device enters PERMANENT FAIL
mode and the following actions are taken in sequence:
1. Precharge, charge, and discharge FETs are turned off.
2. OperationStatus()[PF] = 1
3. The following SBS 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 Status, AFE Config,
AFE VCx, and AFE Data.
5. The black box data of the last three SafetyStatus() changes leading up to PF with the time difference is
written into the black box data flash along with the 1
st
PFStatus() value.
6. The following SBS values are preserved in data flash for failure analysis:
• SafetyAlert()
• SafetyStatus()
• PFAlert()
• PFStatus()
• OperationStatus()
• ChargingStatus()
• GaugingStatus()
• Voltages in DAStatus1()
• Current()
• TS1, TS2, and TS3 from DAStatus2()
7. Data flash writing is disabled (except to store subsequent PFStatus() flags).
8. The SAFE pin is driven high if configured for specific failures and Voltage() is above 3500 mV or there
is a CHG FET (CFETF) or DSG FET (DFETF) failure. The SAFE pin will remain asserted until the
Fuse Blow Timeout expired.
While the device is in PERMANENT FAIL mode, any new SafetyAlert(), SafetyStatus(), PFAlert(), and
PFStatus() flags that are set are added to the permanent fail log. Any new PFStatus() flags that occur
during PERMANENT FAIL mode can trigger the SAFE pin. In addition, new PFStatus() flags are recorded
in the Black Box Recorder 2
nd
and 3
rd
PF Status entries.
4.2 Permanent Failure Configuration
The following configuration registers allow the various permanent failure detection features to be enabled
or disabled. If disabled (default), the feature takes no action including setting flags in PFAlert() or
PFStatus().
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