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TPS536C9: How to modify the IOUT under reporting value on TPS536C9 via PMBus?

Jimmy Gong
Expert 3600 points
Part Number: TPS536C9
Other Parts Discussed in Thread: TPS536C7

Hi team,

i have a question that how to modify the IOUT under reporting value as below picture via PMBus?

My customer want to use BIOS to modify this value but not GUI.

BR,

Jimmy

  • 0
    TI__Expert 8960 points

    Hi Jimmy,

    It can be done by modifying the HIGH_SPEED_BUS_CONFIG_SVID (0xB8) register over PMBus. This register also contains other SVID information. For the specifics of what each bit does, request the TRM/Register map from  .

    Thanks,

    Travis

  • 0
    Prodigy 40 points

    Hello Travis,

    Since it can be changed on the fly, could you please provide the PMBus writing procedure to me? I can read the 0xB8 register over PMBus, but I cannot write it.

    Thank you.

    Willis

  • 0 in reply to Willis Chai
    TI__Expert 8960 points

    Hello Willis,

    If you don't have access to the TPS536C9 TRM, I'd recommend looking at page 17 of the TPS536C7 TRM. That document is publicly available on ti.com. It gives information about PMBus command structure, and the command structure is the same for the TPS536C9.

    www.ti.com/.../sluuc19.pdf

    Thanks,

    Travis

  • 0 in reply to Travis Williams
    Prodigy 40 points

    Hello Travis,

    Yes, I followed the block write protocol to write a block (24 bytes) into the register B8h, but it did not work.

    Do I need to unlock the register for the write command? or I need to do something when I write the data into register B8h?

    Thank you.

    Willis

  • 0 in reply to Willis Chai
    TI__Expert 8960 points

    Hello Willis,

    You can check whether the the device is write protected by looking at the write protect register. Have you tried changing any other registers? Write protect comes disabled by default.

    That particular register only updates the SVID parameters after a power cycle, so you would need to send a "STORE_USER_ALL" command to write to NVM, then restart the device for changes to take effect.

    Also, if a user is going to be manually changing how the system runs in BIOS, that's fine. If an automated program is going to be handling the changes to SVID, please note that the NVM has around 10,000 max writes in its lifetime. This is never an issue in normal operation, but I wouldn't recommend having a BIOS program rewrite the NVM excessively for optimization purposes.

    Thanks,

    Travis 

  • 0 in reply to Travis Williams
    Prodigy 40 points

    Hello Travis,

    If I want to change "IOUT under reporting", do I need to do a power cycle to take effect?

    I think I do not want to write it to NVM. I just want to change it on the register B8h. After AC power cycle, the setting will be rolled back since the controller will reload the setting from NVM. The TRM said that it is on-the-fly for the register B8h. It means I do not need to power cycle, is it right?

    Besides, I can read and write register 00h to change page settings, but I cannot write register B8h. (I can read the register B8h.)

    Willis

  • 0 in reply to Willis Chai
    TI__Expert 8960 points

    Hello Willis,

    You can change it "on the fly" in that you can rewrite the values in RAM at any time. However, many of the fields in this register are only read during power up to set the SVID parameters. In order to make changes take effect on the SVID reporting, the RAM value must be written to NVM, and then the TPS536C9 needs to be power cycled.

    I do not know why you are unable to write to register B8h. I'd recommend checking the WRITE_PROTECT register and ensuring it is set to 0. Also, try writing to it with Fusion GUI and seeing if it works.

  • 0 in reply to Travis Williams
    TI__Expert 8960 points

    Hello Willis,

    I'm closing this thread due to inactivity. If you'd like to reopen the thread, reply to this post.

    Thanks,

    Travis