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Using TPS40193 for 0.9V and 1.1V PS with minimal changes

Ovadia Michelian
Prodigy 10 points
Other Parts Discussed in Thread: TPS40193, SWITCHERPRO

Hi,

I want to use the TPS40193 for 0.9V/15A or 1.1V/15A power supply (Vin=5V). I want same design with minimal changes.

Using the SwitcherPro SW I received 2 designs

I used the SwitcherPro SW to design 0.9V/15A power supply with option to change it to 1.1V/15A. I received 2 designs with few changes (Inductor, 2xResistors and capacitors).

Is it possible to get 2 designs with less changes ?

 

 

 

 

  • 0
    TI__Expert 3875 points

    Hi Ovadia,

    Yes, it is possible to change the design from VOUT=1.1V to VOUT=0.9V by changing just the R2/R3 resistor divider. SwitcherPro can be used to calculate the new values of R2 and R3. Below please find the steps to accomplish this task.

    1) Create the VinMin=5V, VinMax=5V, VOut=1.1V, and IOut=15A design as you did. This will give you the following schematic:

     

    2) Press the "Edit Inputs" button at the top of the "Schematic" tap.

    3) In the "Change Your Inputs" dialog, change Vout to 0.9V (as shown below). Do *not* click the "Allow SwitcherPro to pick components" button. Press the "Apply Changes" button.



    4) SwitcherPro will change the value of R2 from 11.5k to 19.1k  and R3 from 15.4k to 16.9k as shown below:

     

    5) You will notice that SwitcherPro also change the value of R5 from 536Ohm to 562Ohm. But that is not really necessary and you can set R5 back to 536Ohm. Click on R5 and SwitcherPro will display the "Change Compensation" dialog (see screenshot below)

    6) In the dialog (shown below) change R5 from 562 back to 536. Press the "Calculate" button. Press the "Save Changes" button. Finally, close the dialog by pressing the "X" in the top right corner.

    7) Your schematic wil be as shown below. You will notice that the only difference between the original design and the new design are the values of R2 and R3.

    8) Now you can also validate in the "Analysis" -> "Output1" tab to make sure you have a valid output voltage range. In this case you get 0.908V to 0.911V.

    Hope this helps.

    Regards,

    Michael

    Michael Krasnicki
    Analog eLab
    Texas Instruments

  • 0 in reply to Michael Krasnicki
    TI__Intellectual 1280 points

    Technically speaking you could get away with only changing R2.  that's keeps the loop compensation exactly the same as before, just changing the voltage that is fed back into the FB pin.  This might be a little more work in SwitcherPro but much easier in real life because now you have just one resistor to change to set the output voltage. I'd follow Michael's plan above but I'd make a copy of the design before changing the inputs.  this way you'll have the original design as a reference for the comp values.  When you change the inptus on the copied design, you can set all the compensation values (R5,R3, R1, C6,C7,C8) to the exact same values as the original.  Just make sure and leave R2 to the new value. You can copy a design by right clicking it in the design list on the left side and choosing "Make a Copy"