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TPS544C25: Generating 5v output without using PMBus

Part Number: TPS544C25

Hi,

We are planning to use TPS544C25 in our design.

I have check the datasheet and it has VSET pin which can set the output voltage without using PMBus. But supported output voltage using VSET is up to 1.2v only.

We don't want to use PMBus. 

Can we generate 5v output from TPS544C25 without using PMBus?

Thanks,

Lalit

  • Hi ,

    Is there a particular reason you want to use TPS544C25 if you do not intend to use PMBus? Do you intend to use PMBus for anything else? I can help you find an alternate device (w/o PMBus) if you can share your design requirements like Vin, Vout, Iout, Ta and any other requirements, or perhaps you can enter them into WEBENCH Power Designer.

    To answer your question, however, it should be possible to get 5V output without PMBus by creating a resistor divider from the output to the VOUTS+/- pins such that the output is set by the reference (VSET), multipled by the divider factor, i.e. VOUT = VREF * (1+ Rtop/Rbot). For example, use VSET resistor 51.1kohm to GND to set the reference to 1V, then use a divider of Rtop = 10kohm, Rbot = 2.5kohm.

    If you look at the datasheet Section 8.3.6 and Figure 33, it discusses using the R1 and Rbias resistor divider at the DIFFO pin to set the output, however, that approach would still require reprogramming the under- and over-voltage (UV/OV) thresholds through PMBus to avoid the output from being shut off. As indicated in the block diagram, it is the voltage at DIFFO that is detected for UV/OV protection. Thus, the method I mentioned above with a divider to the VOUTS+/- pins would be the better approach.

    Regards,
    Kris

  • Hi Kris,

    Thanks for the inputs.

    Following your inputs, I have created the design using TPS544C25.

    Can you please review the schematic and share your feedback.

    Especially, please check the resistor divider section from output and the VSET connection.

    5V_TPS544C25.pdf

    Thanks,

    Lalit

  • Hi Lalit

       The resistor divider looks ok. Keep the C3295 330pF as a placeholder but do not populate the capacitor.

    To review the overall schematic, I have attached a calculator/checklist to help with this.

    Regards,

    Gerold

    TPS544C25_Calculator_Checklist.xlsx