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TPS549D22: VOUT_COMMAND, Is it really NVM?

Expert 6280 points

Part Number: TPS549D22

 Hello,

 

I have a question about a PMBUS command, “VOUT_COMMAND”, of TPS549D22.

 

From the datasheet, VOUT_COMMAND is NVM. Is it really NVM?

 

I tested it with TPS549D22EVM-784 and Fusion Digital Power Designer.

I changed VOUT_COMMAND value on the Fusion Digital Power Designer and confirmed the Vout was changed as configured.

And push “Store Config to NVM”. It should be saved to NVM.

But after new powering cycle, the it was NOT saved.

 

Regards,

Oba

  • Let me see if I can find out.

    Best  Regards,

    John Tucker

    BSR-CCP LV/MV DC/DC Applications

  • In reply to JohnTucker:

    I found that bit 15 ~ bit 10 are hardcoded and bit 9 ~ bit 0 are NVM. Does this resolve your issue?

    Best  Regards,

    John Tucker

    BSR-CCP LV/MV DC/DC Applications

  • In reply to JohnTucker:

    Further information:

    The Vout will start up to the pinstrap value but will also start up with EPROM setting if the pinstrap is “open” or “0 ohm”. So if you perform the “Store Config to NVM” with the pinstrap open or with 0 ohm, the device will start up to the value of the last Vout setting before you do the “Store Config to NVM”. In other word, the pinstrap takes precedence.

    Let me know if you need further support.

    Best  Regards,

    John Tucker

    BSR-CCP LV/MV DC/DC Applications

  • Expert 6280 points

    In reply to JohnTucker:

    Hello John,

    Thanks for your answer.
    I confirmed the behavior with EVM.
    The device starts up with NVM configurwation if the pinstrap is not only "open" and "0 ohm" but also "187K ohm" and "1.78K Ohm".

    We should update Table 2 on P19 of the datasheet.

    Regards,
    Satoshi Obata 

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