ltc2978 Linear Technology Corporation, ltc2978 Datasheet - Page 25

• Manufacturer Part Number: ltc2978
• Description: Octal Pmbus Power Supply Monitor And Controller With Eeprom
• Manufacturer: Linear Technology Corporation

operaTion
CLEAR_FAULTS
The CLEAR_FAULTS command is used to clear any status
faults that have been set. This command clears all bits in
all unpaged status registers, and the paged status registers
selected by the current PAGE setting. At the same time,
the device negates (clears, releases) its contribution to
ALERTB.
The CLEAR_FAULTS command does not cause a unit that
has latched off for a fault condition to restart.
If the fault condition is present after the fault status is
cleared, the fault status bit shall be set again and the host
notified by the usual means.
Note: this command register does not respond to the
global page command.
WRITE_PROTECT
The WRITE_PROTECT command provides protection
against accidental programming of the LTC2978 command
registers. All supported commands may have their param-
eters read, regardless of the WRITE_PROTECT setting.
WRITE_PROTECT Data Contents
STORE_USER_ALL and RESTORE_USER_ALL
STORE_USER_ALL, RESTORE_USER_ALL commands
provide access to user nonvolatile EEPROM memory.
Once a command is stored in EEPROM, it will be restored
with explicit restore command or when the part emerges
from power-on reset after power is applied. While either
of these commands is being processed, the device will
NACK I
BITS(S) SYMBOL
b[7:0] Write_protect[7:0]
2
C writes.
OPERATION
8’b1000_0000: Disable all writes except
to the WRITE_PROTECT, PAGE, and
STORE_USER_ALL commands.
8’b0100_0000: Disable all writes except
to the WRITE_PROTECT, PAGE, STORE_
USER_ALL, OPERATION, MFR_PAGE_
FF_MASK, and CLEAR_FAULTS.
8’b0000_0000: Enable writes to all
commands.
8’bxxxx_xxxx: All other values reserved.
STORE_USER_ALL. No Data Contents. Accessing this
command will store all operating memory commands
with a corresponding EEPROM memory location. It is
recommended that this command not be executed while
a unit is enabled since all monitoring is suspended while
the operating memory is transferred to EEPROM.
RESTORE_USER_ALL. No Data Contents. Accessing
this command will restore all commands from EEPROM
Memory. It is recommend that this command not be
executed while a unit is enabled since all monitoring is
suspended while the EEPROM is transferred to operating
memory, and intermediate values from EEPROM may not
be compatible with the values initially stored in operating
memory.
CAPABILITY
The CAPABILITY command provides a way for a host
system to determine some key capabilities of the LTC2978.
This one byte command is read only.
CAPABILITY Data Contents
BITS(S) SYMBOL
b[4:0]
b[7]
b[6]
b[5]
Capability_pec
Capability_scl_max
Capability_smb_alert
Reserved
OPERATION
Hard coded to 1 indicating Packet
Error Checking is supported. Reading
the Mfr_config_all_pec_en bit will
indicate whether PEC is currently
required.
Hard coded to 1 indicating the
maximum supported bus speed is
400kHz.
Hard coded to 1 indicating this device
does have an ALERTB pin and does
support the SMBus Alert Response
Protocol.
X: Always returns 0.
LTC2978

2978fa