LTC2972 datasheet(35/112 Pages) LINER

35 / 112 page

LTC2972

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• The next set of words read is the Preamble with 2 bytes packed into a word. Refer to the Fault Log section for details.

• The next set of words read is the Cyclical Loop Data with 2 bytes per word. Refer to the Fault Log section for details.

• Extra reads return zero.

• Interleaved PMBus word and byte commands do not interfere with an ongoing Command Plus block read.

• Interleaved PMBus block reads of MFR_FAULT_LOG will interrupt this command.

Check status to be sure the data just read was all valid:

• Write Mfr_command_plus_pointer = 0x2C with Mfr_command_plus_page = 0 and Mfr_command_plus_id = 0.

• Read data from Mfr_data_plus0 and confirm that Mfr_status_plus_block_peek_failed0 = 0.

Reading Energy Using MFR_COMMAND_PLUS and MFR_DATA_PLUS0

Write Mfr_command_plus_pointer = 0xC0 with Mfr_command_plus_page = 0 and Mfr_command_plus_id = 0.

Read data from Mfr_data_plus_0; each read returns the next data word of the MFR_EIN command:

• Byte_count[15:0] = 0x000C

• Energy_value[15:0]

• Energy_value[31:16]

• Energy_value[47:32]

• Energy_time[15:0]

• Energy_time[31:16]

• Energy_time[47:32]

Peek Operation Using MFR_DATA_PLUS0

Internal words and bytes may be read using Command Plus:

WriteMfr_command_plus_pointer=CMD_CODEwithMfr_command_plus_page=pageandMfr_command_plus_id=0.

The CMD_CODE’s are listed in the PMBus COMMAND SUMMARY table.

Read data from Mfr_data_plus0. Data is always read using a word read. Byte data is returned with upper byte set to 0.

Enabling and Disabling Poke Operations

Poke operations to Mfr_data_plus0 are enabled by writing Mfr_command_plus = 0x0BF6.

Poke operations to Mfr_data_plus0 are disabled by writing Mfr_command_plus = 0x01F6.

Poke operations to Mfr_data_plus1 are enabled by writing Mfr_command_plus = 0x4BF6.

Poke operations to Mfr_data_plus1 are disabled by writing Mfr_command_plus = 0x41F6.

PMBus COMMAND DESCRIPTION

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