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TPS650864: Can I use an external resistor network to adjust BUCK2 on TPS6508640?

Benjamin Uhing
Expert 5495 points
Part Number: TPS650864
Other Parts Discussed in Thread: TPS650861

Hello,

I'm creating a reference design for customers and am considering using the TPS6508640 to power our Xilinx Virtex Ultrascale FPGA. All the default voltages line up well except for VCCINT - I need 0.95V, but the default of the TPS for BUCK2 is either 0.85 V or 0.9V. I know these are adjustable via I2C, but my customers will not be interested in programming power supplies in their factories.

Is it possible to use an external resistor voltage divider on the output of BUCK2 to boost the output voltage by 50 mV (resistor strap to 0.9V, have a network of say 5.56k ohm and 100k ohm) to achieve an output of 0.95V without programming the output via I2C?

Thanks,

Ben

  • 0
    TI__Genius 10885 points

    Hi Ben,

    While this is technically possible, I'm not sure it is recommended.

    With 0.95V as the typical operating voltage, what is the absolute minimum operating voltage of the core rail? If the minimum voltage is below or at 0.9V, it may be acceptable to increase the core voltage using I2C instructions after startup, similar to processors that implement voltage scaling.

    Looping in the product expert to comment.

    Best Regards,

    Rick S.

  • 0
    TI__Genius 17380 points

    Hi Benjamin,

    Another option is to utilize the TPS650861 customer programmable version as you mentioned, but to buy it pre-programmed from a distributor. Both Avnet and Arrow have the capability to program TPS650861 currently. The TPS6508640 settings OTP Generator is available on the TPS650861 product folder, they could change that voltage and send the completed XLS (with any other changes they may find beneficial) to their preferred distributor.