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bq27441 Data Memory Parameter Descriptions
6.4.5 Security Class
6.4.5.1
Codes Subclass
6.4.5.1.1 Sealed to Unsealed
Subclass
Subclass
Offset
Type
Name
Value
Unit
ID
Min
Max
Default
Codes
112
0
H4
Sealed to Unsealed
0x0001
0xFFFF
0x8000
Hex
0001
FFFF
8000
The fuel gauge implements a key-access scheme to transition from SEALED to UNSEALED mode. Once
SEALED via the associated subcommand, a unique set of two keys must be sent to the fuel gauge via the
Control()
command to return to UNSEALED mode. The keys must be sent consecutively, with no other
data being written to the
Control()
register in between.
When in the SEALED mode, the
CONTROL_STATUS [SS]
bit is set; but after the
Sealed to Unsealed
keys are correctly received by the fuel gauge, the
[SS]
bit is cleared. The
Sealed to Unsealed
key has
two identical words stored in ROM with a value of 0x8000 8000. Then,
Control()
should supply 0x8000
and 0x8000 (again) to unseal the part.
After the fuel gauge exits CONFIG UPDATE mode, the fuel gauge will check bit 7 (0x80) in the
Update
Status
register. If bit 7 (0x80) is set, the fuel gauge will be placed into the SEALED state. If the fuel gauge
is placed into SEALED mode on the exit of CONFIG UPDATE mode, the fuel gauge will not be allowed to
go to the UNSEALED state for 4 seconds upon exiting CONFIG UPDATE mode. Any subcommand
greater than 0x001A will restart the 4-second timer.
51
SLUUAC9A – December 2013 – Revised May 2015
Data Memory
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