ADP1053ACPZ-R7 datasheet(40/84 Pages) AD

40 / 84 page

ADP1053

Data Sheet

Rev. A | Page 40 of 84

EEPROM PASSWORD

On power-up, the EEPROM is locked and protected from

accidental writes or erases. Only reads from Page 2 to Page 15

are allowed when the EEPROM is locked. Before any data can

be written (programmed) to the EEPROM, the EEPROM must

be unlocked for write access. After it is unlocked, the EEPROM

is opened for reading, writing, and erasing.

On power-up, Page 0 and Page 1 are also protected from read

access, and the EEPROM must first be unlocked to read these

pages.

Unlock the EEPROM

To unlock the EEPROM, perform two consecutive writes with

the correct password (default = 0xFF) using the EEPROM_

PASSWORD command (Command 0xD5). The EEPROM_

UNLOCKED flag (Bit 4 of Register 0xFEC3) is set to indicate

that the EEPROM is unlocked for write access.

Lock the EEPROM

To lock the EEPROM, write any byte other than the correct

password using the EEPROM_PASSWORD command

(Command 0xD5). The EEPROM_UNLOCKED flag is cleared

to indicate that the EEPROM is locked from write access.

Change the EEPROM Password

To change the EEPROM password, first write the correct password

using the EEPROM_PASSWORD command (Command 0xD5).

Immediately write the new password using the same command.

The password is now changed to the new password.

DOWNLOADING EEPROM SETTINGS TO INTERNAL

REGISTERS

Download User Settings to Registers

The user settings are stored in Page 1 of the EEPROM main

block. These settings are downloaded from the EEPROM into

the registers under the following conditions:

•

On power-up. The user settings are automatically down-

loaded into the internal registers, powering the part up in

a state previously saved by the user.

•

On execution of the RESTORE_USER_ALL command

(Command 0x16). This command allows the user to force

a download of the user settings from Page 1 of the EEPROM

main block into the internal registers.

Download Factory Default Settings to Registers

The factory default settings are stored in Page 0 of the EEPROM

main block. The factory default settings can be downloaded from

the EEPROM into the internal registers using the RESTORE_

DEFAULT_ALL command (Command 0x12).

When this command is executed, the EEPROM password is also

reset to the factory default setting of 0xFF.

SAVING REGISTER SETTINGS TO THE EEPROM

The register settings cannot be saved to the factory default set-

tings located in Page 0 of the EEPROM main block. This is to

prevent the user from accidentally overriding the factory trim

settings and default register settings.

Save Register Settings to User Settings

The register settings can be saved to the user settings located in

Page 1 of the EEPROM main block using the STORE_USER_ALL

command (Command 0x15). Before this command can be

executed, the EEPROM must first be unlocked for writing (see

the Unlock the EEPROM section).

After the register settings are saved to the user settings, any

subsequent power cycle automatically downloads the latest

stored user information from the EEPROM into the internal

registers.

Note that execution of the STORE_USER_ALL command auto-

matically performs a page erase to Page 1 of the EEPROM main

block, after which the register settings are stored in the EEPROM.

Therefore, it is important to wait at least 35 ms for the operation

to complete before executing the next PMBus command.

EEPROM CRC CHECKSUM

As a simple method of checking that the values downloaded

from the EEPROM are consistent with the internal registers,

a CRC checksum is implemented.

•

When the data from the internal registers is saved to the

EEPROM (Page 1 of the main block), the total number

of 1s from all the registers is counted and written into the

EEPROM as the last byte of information. This is called

the CRC checksum.

•

When the data is downloaded from the EEPROM into the

internal registers, a similar counter that sums all 1s from

the values loaded into the registers is saved. This value is

compared with the CRC checksum from the previous

upload operation.

If the values match, the download operation was successful. If

the values differ, the EEPROM download operation failed, and

the EEPROM_CRC fault flag is set (Bit 1 of Register 0xFEC2).

To read the EEPROM CRC checksum value, execute the

EEPROM_CRC_CHKSUM command (Command 0xD1).

This command returns the CRC checksum accumulated in

the counter during the download operation.

Note that the CRC checksum is an 8-bit cyclical accumulator

that wraps around to 0 when 255 is reached.

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