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TPS53667: TPS53667 vs TPS53676 for PMBUS control

Shinya Sawamoto
Expert 5285 points
Part Number: TPS53667
Other Parts Discussed in Thread: TPS53676,

Hello team,

I have a couple of questions to know how different TPS53667 vs TPS53676.

1) Do the both devices equip a same PMBUS control format?

2) Are the both devices have a different SMBUS spec?

Thanks in advance.
S.Sawamoto

  • +1
    TI__Expert 4260 points

    Hi Sawamoto,

    Thank you for your question. The devices follow the command formats based on the PMBus specifications. If you refer to the datasheets of the two devices, you will be able to see the different versions of PMBus specifications used by the two devices. 

    TPS53667: "PMB Power Management Protocol Specification, Part 1, revision 1.1"

    TPS53676: "PMB Power Management Bus (PMBus) Specification, Part I, revision 1.3.1"

    Fundamentally, there shouldn't be a lot of difference between the two command formats.

    Let us take write byte protocol for example. If you look at the TPS53667 datasheet (uses rev 1.1), you can see an example of the PMBus command format used by the device and how it is derived from the PMBus specification from pmbus.com.

    If you look at the PMBus specifications for 1.1 (below), the only difference between this version and the datasheet is the command extension code, which is not in the datasheet. So, you can derive the PMBus command format from the PMBus specification. 

    Since TPS53676 follows Revision 1.3.1, we can see that the PMBus command formats are the same (as attached below from the PMBus specification). 

    So it is safe to say that both the devices use the same PMBus command formats. Specifics of the PMBus command formats for byte, word, etc. can be found in the TPS53667 datasheet (pages 44-46).  

    2. With regards to SMBus, the two different versions of PMBus follow specific versions of SMBus. I have attached details of the specific revision used by each of the devices below. 

    TPS53667 (From PMBus Revision 1.1 Spec) 

    TPS53676 (From PMBus Revision 1.3.1 Spec ) 

    So you can find which specific SMBus spec each of the different devices are based on. 

    Hope that answers your questions, 

    Best Regards, 

    Dhanya Prem

  • 0 in reply to Dhanyasree Prem Sankar
    TI__Expert 5285 points

    Hi Dhanya,

    Thanks a lot for the kind explanation.

    Allow me to ask you an additional question.

    There is a Table.1 VID Table in the TPS53667 datasheet.
    Here are VR12.0 and VR12.5.
    Description of bit[4:0] in register 20h(VOUT mode):
    Both are described, but the Reset value
    It looks like read-only in "00001" (VR 12.0 mode).
    Is it possible to change to “00010” (VR 12.5 mode)?
    * Should it be set by the manufacturer at the time of shipment?

    Thanks in advance.
    S.Sawamoto

  • +1 in reply to Shinya Sawamoto
    TI__Expert 4260 points

    Hello Sawamoto-san, 

    The VOUT_MODE command is a read byte command that tells you which mode is selected. It is read-only. If you are looking to change the mode from VR 12.0 to VR 12.5, you have to change the voltage on the SLEW-MODE pin. I have attached the details of the SLEW-MODE pin and mode selections below. 

    Different mode selections and how to change it: 

    Details on SLEW-MODE pin: 

    Description of the SLEW-MODE pin: 

    You can also use this command (MFR_SPECIFIC_13 (DDh)) to override the SLEW-MODE pin settings and set the VR mode. 

    Hope this answers your questions! Let me know if you have any questions regarding these and if you have additional questions that are not related to these topics, make sure to open a new thread so that people can search up similar topics and find answers.

    Best Regards, 

    Dhanya Prem