Datasheet

LTC2977
65
2977fa
For more information www.linear.com/LTC2977
BULK PROGRAMMING THE USER EEPROM SPACE
The MFR_EE_UNLOCK, MFR_EE_ERASE and MFR_EE_DATA commands provide a method for 3rd party EEPROM
programming houses and end users to easily program the LTC2977 independent of any order dependencies or delays
between PMBus commands. All data transfers are directly to and from the EEPROM and do not affect the volatile RAM
space currently configuring the device.
The first step is to program a master reference part with the desired configuration. MFR_EE_UNLOCK and MFR_EE_DATA
are then used to read back all the data in User EEPROM space as sequential words. This information is stored to the
master programming HEX file. Subsequent parts may be cloned to match the master part using MFR_EE_UNLOCK,
MFR_EE_ERASE and MFR_EE_DATA to transfer data from the master HEX file. These commands operate directly on
the EEPROM independent of the part configurations stored in RAM space. During EEPROM access the part will indicate
that it is busy as described below.
In order to support simple programming fixtures the bulk programming feature only uses PMBus word and byte
commands. The MFR_EE_UNLOCK configures the appropriate access
mode and resets an internal address pointer
allowing a series of word commands to behave as a block read or write with the address pointer being incremented
after each operation. PEC use is optional and is configured by the MFR_EE_UNLOCK operation.
MFR_EE_UNLOCK
The MFR_EE_UNLOCK command prevents accidental EEPROM access in normal operation and configures the required
EEPROM bulk programming mode for bulk initialization, sequential writes, or reads. MFR_EE_UNLOCK augments the
protection provided by write protect. Upon unlocking the part for the required operation, an internal address pointer is
reset allowing a series of MFR_EE_DATA reads or writes to sequentially transfer data, similar to a block read or block
write. The MFR_EE_UNLOCK command can clear or set PEC mode based on the desired level of error protection. An
MFR_EE_UNLOCK sequence consists of writing two unlock codes using two byte-write commands. The following
table documents the allowed sequences. Writing a non-supported sequence locks the part. Reading MFR_EE_UNLOCK
returns the last byte written or zero if the part is locked.
MFR_EE_UNLOCK Data Contents
BIT(S) SYMBOL OPERATION
b[7:0] Mfr_ee_unlock[7:0] To unlock user EEPROM space for Mfr_ee_erase and Mfr_ee_data read or write operations with PEC allowed:
Write 0x2b followed by 0xd4.
To unlock user EEPROM space for Mfr_ee_erase and Mfr_ee_data read or write operations with PEC required:
Write 0x2b followed by 0xd5.
To unlock user and manufacturer EEPROM space for Mfr_ee_data read only operations with PEC allowed:
Write 0x2b, followed by 0x91 followed by 0xe4.
To unlock user and manufacturer EEPROM space for Mfr_ee_data read only operations with PEC required:
Write 0x2b, followed by 0x91 followed by 0xe5.
PMBus COMMAND DESCRIPTION