LTC2972 datasheet(32/112 Pages) LINER

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LTC2972

2972fa

For more information www.linear.com/LTC2972

WRITE_PROTECT

The WRITE_PROTECT command provides protection against accidental programming of the LTC2972 command

registers. All supported commands may have their parameters read, regardless of the WRITE_PROTECT setting, and

the EEPROM contents can also be read regardless of the WRITE_PROTECT settings.

There are two levels of protection:

• Level 1: Nothing can be changed except the level of write protection itself. Values can be read from both pages.

This setting can be stored to EEPROM.

• Level 2: Nothing can be changed except for the level of protection, channel on/off state, clearing of faults and

energy, and PG pin general-purpose output force states. Values can be read from both pages. This setting can be

stored to EEPROM.

WRITE_PROTECT Data Contents

BIT(S) SYMBOL

OPERATION

b[7:0] Write_protect[7:0] 1000_0000b: Level 1 Protection – Disable all writes except to the WRITE_PROTECT, PAGE, MFR_EE_UNLOCK, STORE_

USER_ALL and MFR_COMMAND_PLUS commands.

0100_0000b: Level 2 Protection – Disable all writes except to the WRITE_PROTECT, PAGE, MFR_EE_UNLOCK, STORE_

USER_ALL, OPERATION, MFR_COMMAND_PLUS, MFR_PAGE_FF_MASK, MFR_CLEAR_ENERGY, MFR_PG_GPO, and

CLEAR_FAULTS commands.

0000_0000b: Enable writes to all commands.

xxxx_xxxxb: All other values reserved.

WRITE PROTECT Pin

The WP pin allows the user to write-protect the LTC2972’s configuration registers. The WP pin is active high, and when

asserted it provides Level 2 protection: all writes are disabled except to the WRITE_PROTECT, PAGE, MFR_EE_UNLOCK,

STORE_USER_ALL,OPERATION,MFR_COMMAND_PLUS,MFR_PAGE_FF_MASK,CLEAR_FAULTS,MFR_PG_GPO,and

MFR_CLEAR_ENERGY commands. The most restrictive setting between the WP pin and WRITE_PROTECT command

will override. For example if WP = 1 and WRITE_PROTECT = 0x80, then the WRITE_PROTECT command overrides,

since it is the most restrictive.

WP Pin

State

WRITE_PROTECT

Command Value

Write Protect Level

Low

0x00

No write protection

0x40

Level 2

0x80

Level 1

High

0x00

Level 2

0x40

Level 2

0x80

Level 1

PMBus COMMAND DESCRIPTION

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