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TPS546D24A: TPS546D24A doesn’t support AVSBUS, anything special for AVS in TPS546D24A

David.Wang
Prodigy 30 points
Part Number: TPS546D24A

According to the data sheet, TPS546D24A has AVS feature, but it doesn’t support AVSBUS, which is described in 7.6.9 (19h) capability read only register bit2 (default 0). I just found a few words in the datasheet, and haven’t found any further information in Ti website. Could you help to provide some documents about AVS in TPS546D24A?

TPS546D24A supports PMBUS1.3.1, AVSBUS is one of the features of PMBUS1.3.1, which defines standard commands for AVS. What does it mean TPS546D24Adoesn’t support AVSBUS, anything special for AVS in TPS546D24A?

  • 0
    TI__Mastermind 48200 points

     

    PMBus Part III revision 1.3.1 (AVSBus) is an optional feature for devices that support PMBus 1.3.1.  It is a separate, multi-wire dedicated Point to Point, high-frequency communications bus between the power supply and the device it is powering to allow for rapid adjustment of the power supply's output voltage.

    AVSBus is not the only implementation for Adaptive Voltage Scaling (AVS).  The TPS546x24A family of devices provide Adaptive Voltage Scaling functions through the use of it's PMBus 1.3.1 standard VOUT_COMMAND function over the PMBus communications interface and not through  a separate AVSBus Phy.

    Supporting PMBus 1.3.1 does not require a device to support every function or command of PMBus 1.3.1.  In order to support PMBus 1.3.1 a device must:

    1) Support the required elements of PMBus Part I Revision 1.3.1, which includes conforming to SMBus revision 3.1

    2) Support at least 1 standard (Non MFR_SPECIFIC) PMBus Command detailed in PMBus Part II Revision 1.3.1

    3) Implement Standard PMBus Commands that are supported according to the descriptions detailed in the PMBus Part II Revision 1.3.1

  • 0 in reply to Peter James Miller
    Prodigy 30 points

    Thank you for the explanation, Peter.

    Right, understand TPS546x24A doesn’t need to support all. So it uses i2c bus for AVS control, then VOUT_COMMAND may cover all AVSBUS commands. 

    Regarding the bus specification, I only found a document about AVSBUS on embeddedpowerlabs,  http://www.embeddedpowerlabs.com/Downloads/Intro_To_AVSBus_20151101.pdf, which has information about the standard commands for AVS, but it’s dated 2015, may be too old. Not sure if you can share PMBUS1.3.1 specification, so that I understand what we can do with TPS546x24A for AVS in our design.

  • 0 in reply to David.Wang
    TI__Mastermind 48200 points

     

    the latest PMBus specification files can be obtained from the System Management Interface Forum (SMIF) at the website  

    You will need to create an account.

    The TPS546D24A does not support PMBus PART III (AVSBus) so it will not support the specific commands and dataformats listed  PART III.

    The TPS546D24A does support a wide range of PMBus interface commands, detailed in table 7-6 starting on page 36 of the datasheet -  

    For Output voltage Control, the TPS546D24A implements:

    VOUT_MODE - Defines the data format used for other VOUT related commands

    VOUT_COMMAND - sets the target output voltage using data format described in VOUT_MODE

    VOUT_TRIM - Applies a signed offset voltage to VOUT_COMMAND using the data format described in VOUT_MODE

    VOUT_MARGIN_HIGH / VOUT_MARGIN_LOW - Sets Output Voltage scaling factor (VOUT_MODE = Relative) or overrides VOUT_COMMAND (VOUT_MODE = Absolute) when OPERATION selects MARGIN high or MARGIN Low

    VOUT_SCALE_LOOP - Selects the internal feedback divider to set the output voltage Range 

    VOUT_MIN - Sets a minimum programmable output voltage when output is enabled

    VOUT_MAX - sets a maximum programmable output voltage when output is enabled

    The TPS546D24A also supports telemetry values (PVIN, VOUT, Die Temperature, Output Current) and standard PMBus STATUS bytes (Excluding STATUS_FANS) 

  • 0 in reply to Peter James Miller
    Prodigy 30 points

     Very clear summary, thank you for all the information, Peter!