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Original question:

TPS65311-Q1: what's the main difference between TPS65311-Q1 and TPS65310-Q1

TPS65310A-Q1: Use this IC with low current

Clement Magnien
Prodigy 90 points

Part Number: TPS65310A-Q1

Hello,

The app note for this IC shows how to calculate buck elements for 2 amps approximatively.

What about a design with 200mA? Does  the compensation network  equations are still correct?

Best

  • 0
    TI__Expert 8740 points

    Hello,

    Are you referring to BUCK1 compensation network calculation? We have never seen anyone designing BUCK1 controller for 200mA max current and estimate the sense resistor based on this current. I don't think that this is practical or makes sense to use this device for such a small current. If you design the regulator for higher currents, it would also work fine for any current which is lower than the maximum assumed current. In another words, regulator will be still stable if there is no load on it.

    Regards,

    Murthy

  • 0 in reply to Krishnamurthy Hegde
    Prodigy 90 points

    Hello, 

    Yes Buck1 since others buck don't have compensation network. it was not designed for 200mA but finally it will work with 200mA load, so I am checking if I can reduce inductors size. I just would like to know if all equations are still correct  for this current ( shunt, L, compensation equations). I tried a lot of values for the compensation network but it doesn't seem to have any effect.

    Regards,

  • +1 in reply to Clement Magnien
    TI__Expert 8740 points

    Hello,

    All the datasheet equations are correct if it is used in the way it is intended. You just need to design the regulator for your maximum current and regulator will be stable for all the lower currents. If you put such a small current like 200mA, then you may end up getting some large unrealistic inductor value. Depending on the compensation resistor/capacitors, there will be some difference in phase margin and bandwidth and you have to do bode plot measurements to see the difference. max load transient current has impact to BUCK output capacitor calculation and BUCK output capacitor has some impact to compensation component calculations and hence there will be some changes.

    Regards,

    Murthy