The REG_LOCK command controls writing to the TPS544C26 device. The intent of this command is to provide protection against accidental changes. This command does NOT provide protection against deliberate or malicious changes to a configuration or operation of the device.

After power-on, the user accessible registers with write access are by default under "write protected" state, meaning the response to a write is NACK. The device always acknowledges a read command and responds the data byte accordantly. Only after writing the correct passcodes (multiple writes in the right order) into this REG_LOCK register, the user accessible registers are "unlocked" and the device acknowledges the next write commands. For a device under "unlock" state, the writable registers turn to "write protected" state again if one more write is sent to (B1h) REG_LOCK register, no matter with the correct passcode or wrong one. The user has to go through the complete passcode write combination to unlock the write protection again.

For a device under "unlock" state, VCC power cycling resets the device and the user accessible registers with write access are now under "write protected" state. A RESTORE_USER_ALL command does not change the state.

The expected response for a write into this REG_LOCK register is always NACK, no matter with a correct passcode or a wrong value. For security considerations, the passcodes are not listed in this datasheet. Please contact TI for more details.

All user accessible registers with write access are protected by this mechanism except below ones:

• (03h) CLEAR_FAULTS
• (7Ah) STATUS_VOUT
• (7Bh) STATUS_IOUT
• (7Ch) STATUS_INPUT
• (7Dh) STATUS_TEMPERATURE
• (80h) STATUS_MFR
• (A2h) I2C_ADDR, bit[7] - this bit is reserved for TI usage and always under write protection
• (B1h) REG_LOCK

Return to Supported I²C and Default Values.