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TPS54821 Datasheet vs Webench

Hi,

Data sheet shows pin PWRGD is recommonded to pull up with high value resistor and 5V or less source, but in silution when i use 12V sourse Webench pull up pin PWRGD with 12V source? Is this correct?

Regards,

Surjit

  • Hi Surjit,

    You are right. The PWRGD resistor needs to be connected to a voltage source less than 5.5V. So, if the Vout is lower than 5.5Vout, you can connect the resistor to the Vout pin. But, if both Vin and Vout are higher than 5.5V, then you will need an external source for the resistor. I will work on fixing this issue in WEBENCH and let you know once done. I am expecting to push the correction out by end of next week. In the meanwhile, please ensure the power good resistor in your design is connected to a voltage source less than 5.5V.

    Thanks for notifying us of this issue. Please let me know if I can help with anything else.

    Regards,

    Amod

    WEBENCH(R) Design Center

  • Hi Amod,

    Thanks for your reply, I would like to have +5V output and +12V input, what if I keep PWRGD pin floating/open? As shown in data sheet simplified schematic.

    Regards,

    Surjit

  • Sure Surjit, if you do not need the power good feature, you can leave the pin floating. However, if you do need the feature, you will need to connect it to the output voltage as it is less than 5.5V.

    Regards,

    Amod

  • Surjit, I have pushed the fix for the power good pin to production. You should be able to check this out now. I have connected the power good resistor to a separate voltage source of 5V.

    Regards,
    Amod