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LM3150: Convergence Problem using TINA with the recommended components from the webench

Part Number: LM3150
Other Parts Discussed in Thread: CSD18537NQ5A, TINA-TI

Hello,

I've created a shematic with the webench.

  • Vin=18 - 24 V
  • Vout=13,5V
  • Iout=12A

After that i tried to use the TINA TI transient model of the LM3150 (Rev. A) to simulate the same circuit in TINA TI.

The T3 CSD17320Q5A is a P-Spice Model and the T1 CSD18537NQ5A is a TINA TI model.

Using the transient analysis i get a convergence problem. In the Info is noted: Component: T1.DBD

 WBDesign16_Load Transient-1.pdf

  • The Output resistance is normally around a few Ohms. I just wanted to see if a change of the resistance helps the simulation to compile.

  • Hi,

    Could you please try LM3150 TINA-TI Steady State Reference Design on its page:https://www.ti.com/product/LM3150?

  • Hi,

    thanks for your fast reply. I actually did this during the wait time.

    The model without changes runs fine. Then i replaced my LM3150 model with the one of the stady-state reference.

    Had the same issue. Replaced the Mosfet with the ones from the steady state reference design.

    Now i've got the message: "Convergence problem. Check the analysis parameters! Component: U4.D1"

    Best Regards

    Andreas

  • Hi Iven,

    thanks for your help.

    Copying the Steady State Reference model in my shematic did not work. I changed the parameters of the Reference Design according to the webench design. The simulation is now working.

    The difference between the two designs are the connection of the EN pin and the diode between VCC and BST. In my design the EN pin was floating. Maybe it caused issues. Why is a diode between VCC and BST? 

    Also I only receive my target voltage of 13,5 V at a Vin=24 V (result4). According to the equation 5: Vout=Vfb*(Rfb1+Rfb2)/Rfb1 i should always get the 13,5 V at the output. At Vin=18V i get a lower Vout (result5). Shouldn't the controller regulate the outpult voltage?

    Best Regards 

    Andreas

  • Hi,

    As for the diode between VCC and BST, it looks it's a method to make simulation work well so you can just use the official simulation as an example.

    The lower Vout should be caused by modelling accuracy, it's just for reference and you can verify it in its evaluation board which is free from TI.