PMBus™ Power System Management Protocol …

1 Filename: PMBus_SpecificationLast saved: 06 Sep 2010, 15:18 Power SysteSPart II ww 2010 System PMBus em Management PrSpecification Command LanguaRevision 6 September 2010 gement Interface Forum, Inc. All Rights Rrotocol ge eserved PMBus Power System Mgt Protocol Specification Part II Revision 2010 System Management Interface Forum, Inc. Page 2 of 106 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, noninfringement, or fitness for any particular purpose, or any warranty otherwise arising out of any proposal, specification or sample.

2 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.

3 REVISION HISTORY REV DATE DESCRIPTION EDITED BY 28 Mar 2005 First public release. Robert V. White Artesyn 5 Feb 2007 Second public release. Robert V. White Astec/Artesyn 6 Sep 2010 Third public release Robert V. White Embedded Power Labs PMBus Power System Mgt Protocol Specification Part II Revision 2010 System Management Interface Forum, Inc. Page 3 of 106 All Rights Reserved Table Of Contents 1. Introduction .. 9 Specification Scope.

4 9 Specification Structure .. 9 What Is Included .. 9 What Is Not Included In the PMBus Specification .. 9 Specification Changes Since The Last Revision .. 9 Where To Send Feedback And Comments .. 9 2. Related Documents .. 9 Scope .. 9 Applicable Documents .. 9 Reference Documents .. 10 3. Reference Information .. 10 Signal and Parameter Names .. 10 Numerical Formats .. 10 Decimal Numbers .. 10 Binary Numbers .. 10 Hexadecimal Numbers .. 10 Examples .. 10 Bit And Byte Order .. 11 Bit And Byte Illustrations.

5 11 Abbreviations, Acronyms And 13 4. Addressing And Grouping .. 15 Device Addresses .. 15 General Call Address (Global Broadcast) .. 15 Sending Commands To A Group .. 16 5. Commands .. 16 Commands And Command Codes .. 16 Command 16 Command Execution .. 16 Writing And Reading PMBus Devices .. 16 All Packets Start With A Write Address .. 16 Every Parameter That Can Be Written Must Be Readable .. 16 Commands May Be Read Only .. 17 6. Memory Model, Startup Behavior And Defaults .. 17 Order Of Memory Loading And Precedence.

6 17 The Default And User Stores .. 19 7. Data Formats .. 20 Linear Data Format .. 20 DIRECT Data Format .. 21 Interpreting Received Values .. 21 Sending A Value .. 21 Obtaining The Value Of The m, b, And R 22 Accuracy .. 22 Resolution .. 22 8. Data Formats For The Output Voltage And Output Voltage Related Parameters .. 22 Two Step Process .. 23 VOUT_MODE Command .. 23 Data Bytes For Output Voltage Related Commands .. 24 Linear Mode .. 24 VID Format .. 25 DIRECT Format .. 26 9. Setting And Monitoring The Output Voltage And 27 VOUT_SCALE_LOOP And VOUT_SCALE_MONITOR.

7 27 Setting The Output Voltage .. 29 PMBus Power System Mgt Protocol Specification Part II Revision 2010 System Management Interface Forum, Inc. Page 4 of 106 All Rights Reserved Making And Calibrating Output Current Measurements .. 30 Deleted .. 31 10. Fault Management And Reporting .. 31 Monitoring Operation .. 31 General Description Of PMBus Device Fault Management .. 33 Warning Conditions .. 33 Fault Conditions .. 33 Clearing Warning Or Fault Bits .. 33 Clearing Individual Bits .. 34 Clearing Bits In The STATUS_BYTE And STATUS_WORD.

8 34 General Rules .. 34 Special Case: NONE OF THE ABOVE .. 35 Exceptions .. 35 Immediate Reassertion After Clearing If Condition Is Still Present .. 35 Conceptual View Of How Status Bits And SMBALERT# Work .. 35 Setting Fault And Warning Thresholds .. 36 Setting The Response To A Detected Fault Condition .. 36 Response To Voltage, Temperature And TON_MAX Faults .. 37 Response To Current Faults .. 38 Reporting Faults And Warnings To The Host .. 40 SMBALERT# Signal And Process .. 40 Direct PMBus Device To Host Communication.

9 41 Clearing A Shutdown Due To A Fault .. 41 Data Transmission Faults .. 41 Corrupted Data .. 42 Sending Too Few Bits .. 42 Reading Too Few Bits .. 42 Host Sends Or Reads Too Few Bytes .. 42 Host Sends Too Many Bytes .. 43 Reading Too Many Bytes .. 43 Device Busy .. 43 Data Content Faults .. 44 Improperly Set Read Bit In The Address Byte .. 44 Unsupported Command Code .. 44 Invalid Or Unsupported Data .. 44 Data Out Of Range Fault .. 45 Reserved 45 11. Address, Memory, Communication And Capability Related Commands.

10 46 WRITE_PROTECT .. 46 STORE_DEFAULT_ALL .. 46 RESTORE_DEFAULT_ALL .. 46 STORE_DEFAULT_CODE .. 47 RESTORE_DEFAULT_CODE .. 47 STORE_USER_ALL .. 47 RESTORE_USER_ALL .. 48 STORE_USER_CODE .. 48 RESTORE_USER_CODE .. 48 PAGE .. 49 PHASE .. 50 CAPABILITY .. 51 QUERY .. 51 PAGE_PLUS_WRITE .. 52 PAGE_PLUS_READ .. 53 12. On, Off And Margin Testing Related Commands .. 53 OPERATION .. 53 54 PMBus Power System Mgt Protocol Specification Part II Revision 2010 System Management Interface Forum, Inc.