LTC3883 Datasheet, PDF (31/112 Pages) Linear Technology – Single Phase Step-Down DC/DC Controller with Digital Power System Management

LTC3883/LTC3883-1
PMBus Command Summary
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 reserved 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 circumstances 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.
Table 2. Summary (Note: The Data Format abbreviations are detailed at the end of this table.)
COMMAND NAME
PAGE
OPERATION
ON_OFF_CONFIG
CLEAR_FAULTS
WRITE_PROTECT
STORE_USER_ALL
RESTORE_USER_ALL
CAPABILITY
VOUT_MODE
CMD
CODE DESCRIPTION
0x00 Provides integration with multi-page PMBus
devices.
0x01 Operating mode control. On/off, margin high and
margin low.
0x02 RUN pin and PMBus bus on/off command
configuration.
0x03 Clear any fault bits that have been set.
0x10 Level of protection provided by the device
against accidental changes.
0x15 Store user operating memory to EEPROM.
0x16 Restore user operating memory from EEPROM.
0x19 Summary of PMBus optional communication
protocols supported by this device.
0x20 Output voltage format and exponent (2^–12).
DATA
TYPE FORMAT
R/W Byte Reg
R/W Byte Reg
R/W Byte Reg
Send Byte
R/W Byte Reg
Send Byte
Send Byte
R Byte
Reg
R Byte
Reg
UNITS
VOUT_COMMAND
0x21 Nominal output voltage set point.
R/W Word L16
V
VOUT_MAX
0x24 Upper limit on the output voltage the unit can
command regardless of any other commands.
VOUT_MARGIN_HIGH
0x25 Margin high output voltage set point. Must be
greater than VOUT_COMMAND.
VOUT_MARGIN_LOW
0x26 Margin low output voltage set point. Must be
less than VOUT_COMMAND.
VOUT_TRANSITION_RATE 0X27 Rate the output changes when VOUT
commanded to a new value.
FREQUENCY_SWITCH
0x33 Switching frequency of the controller.
R/W Word L16
R/W Word L16
R/W Word L16
R/W Word L11
R/W Word L11
V
V
V
V/ms
kHz
DEFAULT
NVM VALUE PAGE
0x00
64
Y
0x80
67
Y
0x1E
66
NA
93
Y
0x00
64
NA
101
NA
101
0xB0
91
2^–12
71
0x14
Y
1.0
73
0x1000
Y
5.5
72
0x5800
Y
1.05
72
0x10CD
Y
0.95
73
0x0F33
Y
0.25
80
AA00
Y
350
70
0xFABC
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