Datasheet

AT30TSE752A/754A/758A [DATASHEET]
Atmel-8854G-DTS-AT30TSE752A-754A-758A-Datasheet_102014
32
7. Register Locking
All Volatile and Nonvolatile Configuration and Limit Registers (the Configuration Register, T
LOW
Limit Register, T
HIGH
Limit Register, Nonvolatile Configuration Register, Nonvolatile T
LOW
Limit Register, and Nonvolatile T
HIGH
Limit Register)
can be locked from data changes by utilizing the RLCK bit in the Nonvolatile Configuration Register. This provides the
ability to lock the registers and protect them from inadvertent or erroneous data changes, giving system designers a
more robust and secure temperature sensing solution compared to other industry devices. The RLCK bit can be reset so
that the various registers can be modified if needed. Resetting of the RLCK bit is done by writing to the Nonvolatile
Configuration Register and changing the RLCK bit back to a Logic 0 state. When the registers are locked, only the RLCK
bit of the Nonvolatile Configuration Register can be altered, and any attempts at changing other bits in the Nonvolatile
Configuration Register will be ignored.
In addition, the Volatile and Nonvolatile Configuration and Limit Registers can be permanently locked down by using the
RLCKDWN bit in the Nonvolatile Configuration Register. When the RLCKDWN bit is set, the Volatile and Nonvolatile
Configuration and Limit Registers will be permanently locked down so that they can never be modified again. Unlike the
RLCK bit, the RLCKDWN bit is one-time programmable and cannot be reset. Therefore, the lockdown mechanism is not
reversible. The RLCKDWN bit takes priority over the RLCK bit (see Table 7-1).
Having the ability to permanently lock down the Volatile and Nonvolatile Configuration and Limit Registers provides the
ability to have a pre-defined, secure, and unchangeable temperature sensing solution for applications dealing with
liability, risk, or safety concerns.
The register locking is not affected by power cycles or reset operations, including the General Call Reset; therefore, if a
device is power cycled or reset with the registers in the locked or locked-down state, then the registers will remain locked
or locked-down when normal device operation resumes.
Table 7-1. Register Locking
RLCKDWN RLCK Locking Status
0 0 Volatile and Nonvolatile Configuration and Limit Registers are unlocked and can be modified.
0 1
Volatile and Nonvolatile Configuration and Limit Registers are locked and cannot be modified
except for the RLCK bit of the Nonvolatile Configuration Register which can be reset.
1 0
Volatile and Nonvolatile Configuration and Limit Registers are permanently locked down and
can never be modified again.
1 1
Volatile and Nonvolatile Configuration and Limit Registers are permanently locked down and
can never be modified again.