Filename: PMBus_Specification_Part_II_Rev_1_3_1_20150313A.docx
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PMBus™
Power System Management Protocol
Specification
Part II – Command Language
Revision 1.3.1
13 March 2015
www.powerSIG.org
© 2015 System Management Interface Forum, Inc. – All Rights Reserved
PMBus Power System Mgt Protocol Specification – Part II – Revision 1.3.1
© 2015 System Management Interface Forum, Inc. Page 2 of 121
All Rights Reserved
DISCLAIMER
This specification is provided “as is” with no warranties whatsoever
, whether express, implied or
statutory
, including but not limited to any warranty of merchantability, non-infringement, or
fitness for any particular purpose
, or any warranty otherwise arising out of any proposal,
specification or sample.
In no event will any specification co
-owner be liable to any other party for any loss of profits,
loss of use, incidental, consequential, indirect, or special damages arising out of this
specification
, whether or not such party had advance notice of the possibility of such damages.
Further, no warranty or representation is made or implied relative to freedom from infringement
of any third party patents when practicing the specification.
Other product and corporate names may be trademarks of other companies and are used only
for explanation and to the owner’s benefit, without intent to infringe.
REVISION HISTORY
REV DATE DESCRIPTION EDITED BY
1.0
28 Mar 2005
First public release.
Robert V. White
Artesyn Technologies
1.1
5 Feb 2007
Second public release.
Robert V. White
Astec/Artesyn
1.2
6 Sep 2010
Third public release
Robert V. White
Embedded Power Labs
1.3
18 March 2014
Fourth public release
Robert V. White
Embedded Power Labs
1.3.1
13 March 2015
Fifth public release
Robert V. White
Embedded Power Labs
PMBus Power System Mgt Protocol Specification – Part II – Revision 1.3.1
© 2015 System Management Interface Forum, Inc. Page 3 of 121
All Rights Reserved
Table Of Contents
1. Introduction ........................................................................................................................................... 11
1.1. Specification Scope ................................................................................................................. 11
1.1.1. Specification Structure ................................................................................................ 11
1.1.2. What Is Included ......................................................................................................... 11
1.1.3. What Is Not Included In the PMBus Specification ...................................................... 11
1.2. Specification Changes Since The Last Revision ..................................................................... 11
1.3. Where To Send Feedback And Comments ............................................................................. 11
2. Related Documents .............................................................................................................................. 11
2.1. Scope ....................................................................................................................................... 11
2.2. Applicable Documents ............................................................................................................. 12
2.3. Reference Documents ............................................................................................................. 12
3. Reference Information .......................................................................................................................... 12
3.1. Signal and Parameter Names ................................................................................................. 12
3.2. Numerical Formats .................................................................................................................. 12
3.2.1. Decimal Numbers ....................................................................................................... 12
3.2.2. Floating Point Numbers .............................................................................................. 12
3.2.3. Binary Numbers .......................................................................................................... 12
3.2.4. Hexadecimal Numbers ............................................................................................... 13
3.2.5. Examples .................................................................................................................... 13
3.3. Bit And Byte Order ................................................................................................................... 13
3.4. Bit And Byte Illustrations .......................................................................................................... 13
3.5. Abbreviations, Acronyms And Definitions ............................................................................... 15
4. Addressing And Grouping .................................................................................................................... 17
4.1. Device Addresses .................................................................................................................... 17
4.2. General Call Address (Global Broadcast) ............................................................................... 17
4.3. Sending Commands To A Group ............................................................................................ 17
4.4. ZONE_READ And ZONE_WRITE .......................................................................................... 18
5. Commands ........................................................................................................................................... 18
5.1. Commands And Command Codes .......................................................................................... 18
5.2. Command Extensions ............................................................................................................. 18
5.3. Command Execution ............................................................................................................... 18
5.4. Writing And Reading PMBus Devices ..................................................................................... 18
5.4.1. All Packets Start With A Write Address ...................................................................... 18
5.4.2. Every Parameter That Can Be Written Must Be Readable ........................................ 18
5.4.3. Commands May Be Read Only .................................................................................. 19
6. Memory Model, Startup Behavior And Defaults ................................................................................... 19
6.1. Order Of Memory Loading And Precedence ........................................................................... 19
6.2. The Default And User Stores ................................................................................................... 21
7. Numeric Data Formats ......................................................................................................................... 22
7.1. Summary ................................................................................................................................. 22
7.2. Restrictions .............................................................................................................................. 23
7.3. LINEAR11 Numeric Format ..................................................................................................... 23
7.4. DIRECT Data Format .............................................................................................................. 24
7.4.1. Interpreting Received Values ..................................................................................... 24
7.4.2. Sending A Value ......................................................................................................... 24
PMBus Power System Mgt Protocol Specification – Part II – Revision 1.3.1
© 2015 System Management Interface Forum, Inc. Page 4 of 121
All Rights Reserved
7.4.3. Obtaining The Value Of The m, b, And R Coefficients ............................................... 24
7.5. IEEE-754 Floating Point .......................................................................................................... 25
7.6. IEEE-754 Half Precision Floating Point ................................................................................... 25
7.6.1. IEEE-754 Single Precision Floating Point Format ...................................................... 25
7.6.2. Floating Point Value Restrictions ............................................................................... 25
7.7. Manufacturer Specific Numeric Data Formats ........................................................................ 26
7.8. Accuracy .................................................................................................................................. 26
7.9. Resolution ................................................................................................................................ 26
8. Data Formats For The Output Voltage And Output Voltage Related Parameters ............................... 26
8.1. Restrictions .............................................................................................................................. 26
8.1.1. Positive And Negative Output Voltages ..................................................................... 26
8.1.2. Floating Point Format ................................................................................................. 27
8.2. Two Step Process ................................................................................................................... 27
8.3. VOUT_MODE Command ........................................................................................................ 27
8.3.1. Mode Selection ........................................................................................................... 27
8.4. Data Bytes For Output Voltage Related Commands............................................................... 28
8.4.1. LINEAR16 Formats .................................................................................................... 29
8.4.1.1. ULINEAR16 Format .................................................................................... 29
8.4.1.2. SLINEAR16 Format .................................................................................... 29
8.4.2. VID Format ................................................................................................................. 29
8.4.3. DIRECT Format .......................................................................................................... 30
8.4.4. IEEE-754 Half Precision Floating Point ...................................................................... 31
8.5. Absolute Value And Relative Value Voltage Related Commands .......................................... 31
8.5.1. Absolute Value Mode Data Bytes ............................................................................... 32
8.5.2. Relative Value ............................................................................................................ 32
8.5.3. Relative Value Mode Notes ........................................................................................ 33
9. Setting And Monitoring The Output Voltage And Current .................................................................... 33
9.1. VOUT_SCALE_LOOP And VOUT_SCALE_MONITOR ......................................................... 33
9.2. Setting The Output Voltage ..................................................................................................... 35
9.3. Switching Between PMBus and AVSBus Control Of The Output Voltage .............................. 37
9.4. Making And Calibrating Output Current Measurements ......................................................... 38
9.5. Deleted .................................................................................................................................... 39
10. Fault Management And Reporting........................................................................................................ 39
10.1. Monitoring Operation ............................................................................................................... 39
10.2. General Description Of PMBus Device Fault Management .................................................... 40
10.2.1. Warning Conditions .................................................................................................... 41
10.2.2. Fault Conditions .......................................................................................................... 41
10.2.3. Clearing Warning Or Fault Bits ................................................................................... 41
10.2.4. Clearing Individual Bits ............................................................................................... 42
10.2.5. Clearing Bits In The STATUS_BYTE And STATUS_WORD ..................................... 42
10.2.5.1. General Rules ............................................................................................. 42
10.2.5.2. Exceptions .................................................................................................. 42
10.2.6. Immediate Reassertion After Clearing If Condition Is Still Present ............................ 43
10.3. Conceptual View Of How Status Bits And SMBALERT# Work ............................................... 43
10.4. Setting Fault And Warning Thresholds .................................................................................... 44
10.5. Setting The Response To A Detected Fault Condition ........................................................... 44
10.5.1. Response To Voltage, Temperature And TON_MAX Faults ..................................... 45
10.5.2. Response To Current Faults ...................................................................................... 46
PMBus Power System Mgt Protocol Specification – Part II – Revision 1.3.1
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All Rights Reserved
10.6. Reporting Faults And Warnings To The Host .......................................................................... 48
10.6.1. SMBALERT# Signal And Process .............................................................................. 48
10.6.2. Direct PMBus Device To Host Communication .......................................................... 49
10.7. Clearing A Shutdown Due To A Fault ..................................................................................... 49
10.8. Data Transmission Faults ........................................................................................................ 49
10.8.1. Corrupted Data ........................................................................................................... 50
10.8.2. Sending Too Few Bits ................................................................................................ 50
10.8.3. Reading Too Few Bits ................................................................................................ 50
10.8.4. Host Sends Or Reads Too Few Bytes ....................................................................... 50
10.8.5. Host Sends Too Many Bytes ...................................................................................... 51
10.8.6. Reading Too Many Bytes ........................................................................................... 51
10.8.7. Device Busy ................................................................................................................ 51
10.9. Data Content Faults ................................................................................................................. 52
10.9.1. Improperly Set Read Bit In The Address Byte............................................................ 52
10.9.2. Unsupported Command Code .................................................................................... 52
10.9.3. Invalid Or Unsupported Data ...................................................................................... 52
10.9.4. Data Out Of Range Fault ............................................................................................ 53
10.9.5. Reserved Bits ............................................................................................................. 53
11. Address, Memory, Communication And Capability Related Commands ............................................. 54
11.1. WRITE_PROTECT .................................................................................................................. 54
11.2. STORE_DEFAULT_ALL ......................................................................................................... 54
11.3. RESTORE_DEFAULT_ALL .................................................................................................... 54
11.4. STORE_DEFAULT_CODE ..................................................................................................... 55
11.5. RESTORE_DEFAULT_CODE ................................................................................................ 55
11.6. STORE_USER_ALL ................................................................................................................ 56
11.7. RESTORE_USER_ALL ........................................................................................................... 56
11.8. STORE_USER_CODE ............................................................................................................ 56
11.9. RESTORE_USER_CODE ....................................................................................................... 57
11.10. PAGE ....................................................................................................................................... 57
11.11. PHASE ..................................................................................................................................... 59
11.12. CAPABILITY ............................................................................................................................ 59
11.13. QUERY .................................................................................................................................... 60
11.14. PAGE_PLUS_WRITE .............................................................................................................. 61
11.15. PAGE_PLUS_READ ............................................................................................................... 61
11.16. Zone Operation Commands .................................................................................................... 62
11.16.1. ZONE_CONFIG ...................................................................................................... 62
11.16.2. ZONE_ACTIVE ....................................................................................................... 63
12. On, Off And Margin Testing Related Commands ................................................................................. 64
12.1. OPERATION............................................................................................................................ 64
12.1.1. OPERATION Command Bit [7] .................................................................................. 64
12.1.2. OPERATION Command Bit [6] .................................................................................. 65
12.1.3. OPERATION Command Bits [5:4] .............................................................................. 65
12.1.4. OPERATION Command Bits [3:2] .............................................................................. 65
12.1.5. OPERATION Command Bit [1] .................................................................................. 65
12.1.6. OPERATION Command Bit [0] .................................................................................. 66
12.1.7. OPERATION Command Invalid Data ......................................................................... 66
12.2. ON_OFF_CONFIG .................................................................................................................. 67
13. Output Voltage Related Commands ..................................................................................................... 69
