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TPS650864: Feedback loop

Part Number: TPS650864

Hi,

There are FBVOUT pins for every buck convereters (BUCK1-BUCK6) which are connected after output inductor. While doing Power Integrity DC drop analysis , can we consider source point after the inductor. Otherwise, we have to consider the DC resistance values of that series output inductor? we want to know whether this TPS65086401RSKT will compensate the voltage drop occurring across the inductor as the feedback is connected after the inductor.

  • Gnanaprabhu,

    The BUCK will regulate the high and low side FET drivers such that the point that FBVOUT is connected to is at the set output voltage. You do not need to account for the DC drop across the inductor. The real concern would be the DC drop between the inductor and the load due to trace length. With BUCK controllers such as BUCKs 1, 2, and 6 you can place the FET and inductor closer to the load, so that there is minimal voltage drop.
  • Hi Nick Jakse,

    Thanks for your information. 

    BUCK 1,2 & 6 are okay. what about BUCK 3,4 and 5. It will also compensate the drop across the inductor connected in series with LX pins.

    If we connect FBVOUT at the load point whether it will compensate the drop across inductor to load. Because in our design inductor to load distance is about 1500 mils and we have placement keep out areas so that we can not place PMIC very close to xilinx zync processor(load).

  • Gnanaprabhu,

    BUCKs 3-5 will also account for the drop across the inductor. If you connect FBVOUT to the load point it will also account for the drop from the inductor to the load; this is true for any of the BUCKs. I only pointed out BUCKs 1, 2, and 6 because they have external FETs which can be placed closer to load.
  • Thank you for your information