Safety Cell Undervoltage Permanent Fail
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SLUUBD3D–September 2015–Revised September 2018
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Permanent Fail
AFE_OVRD (Bit 2): AFE Override
1 = Enabled
0 = Disabled (default)
AFEC (Bit 1): AFE Communication
1 = Enabled
0 = Disabled (default)
AFER (Bit 0): AFE Register
1 = Enabled
0 = Disabled (default)
Class Subclass Name Format
Size in
Bytes
Min Max Default Unit
Settings Fuse PF SAFE C Hex 1 0x00 0xFF 0x00 —
7 6 5 4 3 2 1 0
RSVD RSVD RSVD RSVD RSVD RSVD DFW IFC
RSVD (Bits 7–2): Reserved
DFW (Bit 1): Data flash write
1 = Enabled
0 = Disabled (default)
IFC (Bit 0): Instruction flash checksum
1 = Enabled
0 = Disabled (default)
The bq78350-R1 has a minimum voltage required to attempt to blow a fuse through SAFE activation. This
is a pack-based value of 3500 mV. Voltage scaling (VSCALE) should be enabled if the supported battery
pack voltage is higher than 32767 mV. This value is automatically internally adjusted for any VSCALE
setting. FET failures bypass this requirement to activate SAFE.
4.4 Safety Cell Undervoltage Permanent Fail
The bq78350-R1 uses the UV Protection function of the companion AFE for this feature and can be
configured to permanently disable the battery in the case of severe undervoltage in any of the cells. This
feature cannot be disabled.
The voltage threshold setting is set in AFE SUV:Threshold, which the device will map to the available
settings in the companion AFE with the maximum setting of 3131 mV and the minimum of 1568 mV.
The delay timing configuration for this feature is combined in the same register with the delay time of the
Safety Overvoltage feature.
Status Condition Action
Normal AFEStatus() [UV] = 0 PFStatus()[SUV] = 0
Trip AFEStatus() [UV] = 1
PFStatus()[SUV] = 1
BatteryStatus()[FD] = 1
BatteryStatus()[TDA] = 1
BatteryStatus()[TCA] = 1
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