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WEBENCH® Tools/TPS40400: Set IOUT_OC_FAULT and IOUT_CAL_GAIN unsucessfully

Part Number: TPS40400

Tool/software: WEBENCH® Design Tools

use the GUI set IOUT_CAL_GAIN,IOUT_CAL_OFFSET and IOUT_OC_FAULT unsucessfully. The GUI dispaly"TPS40401 @ 127d: IOUT_OC_FAULT_LIMIT [0x46]: wrote 15.0 A [0xF81E] to the device and it was ACKed, but a write verification read back returned 15.5 A [0xF81F]". And set IOUT_OC_WARN is OK. I have enable write protection for all command. I don't know why?

  • Hello,

    Can you confirm the value of IOUT_OC_WARN_LIMIT when you are writing this value to IOUT_OC_FAULT_LIMIT? IOUT_OC_WARN_LIMIT must be greater than or equal to IOUT_OC_FAULT_LIMIT at all times or the device will set the CML bit in the STATUS_BYTE and the invalid data (ivd) bit in the STATUS_CML registers as well as assert the SMBALRT signal. Can you confirm this value?

    Best regards, 

    Layne J

  • Hello,

             Are you sure that  IOUT_OC_WARN_LIMIT must be greater than or equal to IOUT_OC_FAULT_LIMIT at all times? I think that  IOUT_OC_WARN_LIMIT must be less than or equal to IOUT_OC_FAULT_LIMIT at all times. So i have set IOUT_OC_WARN_LIMIT to 14A and then set IOUT_OC_FAULT_LIMIT to 15A. But it dispaly information as follow"TPS40401 @ 127d: IOUT_OC_FAULT_LIMIT [0x46]: wrote 15.0 A [0xF81E] to the device and it was ACKed, but a write verification read back returned 15.5 A [0xF81F]".

            Also I have done the test for your advise. I set IOUT_OC_WARN_LIMIT to 16A and then set IOUT_OC_FAULT_LIMIT to 15A. The device set the CML bit in the STATUS_BYTE and the invalid data (ivd) bit in the STATUS_CML registers.

           The GUI display"10:11:26.295: TPS40401 @ 127d: IOUT_OC_WARN_LIMIT [0x4A]: wrote 16.0 A [0xF820] to RAM.

                                     10:11:29.669: TPS40401 @ 127d: IOUT_OC_FAULT_LIMIT [0x46]: wrote 16.0 A [0xF820] to the device and it was ACKed, but a write verification read back returned 15.5 A [0xF81F]

                                     10:12:37.450: TPS40401 @ 127d: IOUT_OC_FAULT_LIMIT [0x46]: wrote 15.0 A [0xF81E] to the device and it was ACKed, but a write verification read back returned 15.5 A [0xF81F]."

  • Hello,

            I do anther test. use TPS40400 to set IOUT_OC_FAULT,IOUT_CAL_GAIN and IOUT_CAL_OFFSET sucessfully. Then import the file which save from TP40401 project  to TPS40400. I find that the parameter set unsucessfully. Then import TPS40400 file and find that the paramer could not return the previous value. why?  does it have any switch in TPS40401?

            Do TPS40401 have PMBUS command which can return the configure to default value?

  • Hello,

    My apologies, you are correct that IOUT_OC_FAULT_LIMIT must be greater than IOUT_OC_WARN_LIMIT. 

    As for uploading the TPS40400 file to the TPS40401, this will likely not work as TPS40400 has a few differences from TPS40401 in regards to the PMBus functionality. I would recommend reading over Peter's reply in this thread for a better understanding of the differences. 

    When you were able to write the IOUT_OC_FAULT on the TPS40400 was the write protect status set to enable writes? If you have write protect set you will not be able to change IOUT_OC_FAULT and from my understanding the write protect bit is permanent, as seen in section 7.6.44.2 of the TPS40400 datasheet.

    Best regards,

    Layne J

  • Hello:

            I think that i know the reason. Thank you very much!