Datasheet

LTC3880/LTC3880-1
32
3880fc
For more information www.linear.com/LTC3880
PMBUS COMMANDS
The following tables list supported PMBus commands and
manufacturer specific commands. A complete description
of these commands can be found in the “PMBus Power
System Mgt Protocol Specification – Part II – Revision
1.1”. Users are encouraged to reference this specification.
Exceptions or manufacturer specific implementations
are listed below in Table 2. Floating point values listed
in the “DEFAULT VALUE” column are either Linear 16-bit
Signed (PMBus Section 8.3.1) or Linear_5s_11s (PMBus
Section 7.1) format, whichever is appropriate for the com
-
mand. All commands from 0xD0 through 0xFF not listed
in this table are implicitly reser
ved by the manufacturer
.
Users should avoid blind writes within this range of com
-
mands to avoid undesired operation of the part. All com-
mands from 0x00 through 0xCF not listed in this table are
implicitly not supported by the manufacturer. Attempting to
access non-supported or reserved commands may result
in a CML command fault event. All output voltage settings
and measurements are based on the VOUT_MODE setting
of 0x14. This translates to an exponent of 2
–12
.
If PMBus commands are received faster than they are be-
ing processed, the part may become too busy to handle
new commands. In these cir
cumstances the part follows
the protocols defined in the PMBus Specification v1.1,
Part II, Section 10.8.7, to communicate that it is busy
.
The part includes handshaking features to eliminate busy
errors and simplify error handling software while ensur
-
ing robust communication and system behavior. Please
refer to the subsection titled PMBus Communication and
Command Processing in the Applications Information
section for further details.
COMMAND NAME
CMD
CODE DESCRIPTION TYPE PAGED
DATA
FORMAT UNITS NVM
DEFAULT
VALUE PAGE
PAGE 0x00 Channel or page currently selected for any
command that supports paging.
R/W Byte N Reg 0x00
63
OPERATION 0x01 Operating mode control. On/off, margin high and
margin low.
R/W Byte Y Reg Y 0x80
67
ON_OFF_CONFIG 0x02 RUN pin and PMBus bus on/off command
configuration.
R/W Byte Y Reg Y 0x1E
66
CLEAR_FAULTS 0x03 Clear any fault bits that have been set. Send Byte N NA
91
WRITE_PROTECT 0x10 Level of protection provided by the device
against accidental changes.
R/W Byte N Reg Y 0x00
63
STORE_USER_ALL 0x15 Store user operating memory to EEPROM. Send Byte N NA
101
RESTORE_USER_ALL 0x16 Restore user operating memory from EEPROM. Send Byte N NA
101
CAPABILITY 0x19 Summary of PMBus optional communication
protocols supported by this device.
R Byte N Reg 0xB0
90
VOUT_MODE 0x20 Output voltage format and exponent (2
–12
). R Byte Y Reg 2
–12
0x14
71
VOUT_COMMAND 0x21 Nominal output voltage set point. R/W Word Y L16 V Y 1.0
0x1000
72
VOUT_MAX 0x24 Upper limit on the commanded output voltage
including VOUT_MARGIN_HIGH.
R/W Word Y L16 V Y 4.096 ch0
0x4189
5.5 ch1
0x5800
71
VOUT_MARGIN_HIGH 0x25 Margin high output voltage set point. Must be
greater than VOUT_COMMAND.
R/W Word Y L16 V Y 1.05
0x10CD
72
VOUT_MARGIN_LOW 0x26 Margin low output voltage set point. Must be
less than VOUT_COMMAND.
R/W Word Y L16 V Y 0.95
0x0F33
72
VOUT_TRANSITION_RATE 0X27 Rate the output changes when VOUT
commanded to a new value.
R/W Word Y L11 V/ms Y 0.25
AA00
78
Table 2. Summary (Note: The Data Format abbreviations are detailed at the end of this table.)
PMBus COMMAND SUMMARY