• State Resolved
  • Locked Locked
  • Replies 2 replies
  • Answers 1 answer
  • Subscribers 38 subscribers
  • Views 1230 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

LM5118 WEBENCH simulation limits

Tom Barclay
Prodigy 80 points


Basic design is WEBENCH for 5 to 36V in and 15V at 2A out. WEBENCH will not provide any results if I run dv/dt and set the output current to be low (100mA) at nominal input voltages of 12 or 24V.  It does not provide any error messages. I suspect its outside the operating range due to duty cycle restrictions or similar. Is there a way to force WEBENCH to simulate this state or at least provide an error or warning message to guide me on the problem ?. Otherwise its build a prototype and test that which seems to defeat the point of the simulator. Any help gratefully received

  • 0
    TI__Mastermind 41310 points

    Tom,

    We will investigate the behavior of the dv/dt panel. As a short term solution, you could use the Schematic Editor and run a startup simulation with your required values. Click on the Edit icon and select the green "Edit this design" button on the lower left hand side of the pop up window. This will create a copy of the WEBENCH® generated design in the Schematic Editor (Startup simulation only, no CC functions supported). Click on the Vin1 input and change it to 12V.

    Next, click on the Load (Rload) and change it to 150Ohms (for the 100mA case).

    Click on the simulation button (the red sine wave) and run the simulation. You can look at any of the results using the probe list or by simply clicking on the node or component in the schematic.

    You can now update Vin to 24V and re-run the simulation. Please remember that this is a simulation only interface. You can always return to the original design by using the MyDesigns link in the WEBENCH® window (upper left hand corner).

  • 0
    TI__Intellectual 2155 points

    Hi Tom,

    Your design at 100mA is likely entering DCM, discontinous conduction mode, as the operating mode for the power supply. In the OpVals view (the dV/dt button), we are showing limited calculations when the system enters DCM. I think in general WEBENCH tries to design power supplies to operate in CCM.

    You can perhaps force CCM in the calculations by changing the inductor value of your 2A design. Select a CUSTOM component for L1 in the BOM page. A larger inductor will result in a smaller current ripple, which will cause the system to more likely be in CCM.

    Or you can try to create a new design from the product folder page

    www.ti.com/product/LM5118
    with 100mA as the design output current.