LM5018 SIM does not match input requirements

Ron Kolarovic

Other Parts Discussed in Thread: LM5018, TINA-TI, LM5017

Pretty straight formward. Set up for 32-90Vin, 30V @ 0.25A output. Webench produced 3 solutions and I picked the LM5018. I used the default component calues but the sims do not produce output voltages as expected even though no errors are indicated. For example the load ransient does show a -/0.25A load but the output voltage is only at approx 7V (should be 30V). When I probe Vin it indicates a maximum of 75V and a nominal of 61, what gives with that? Similar funkiness with the startup and steady state.

Can this get resolved quickly? I need to proceed with this design and if I can't trust a sim with default components then I can't trust the result.

over 12 years ago

0 Nikhil Gupta (Product Folder Models) over 12 years ago

TI__Mastermind 39210 points

Hi Ron,

It looks like there is a bug in the simulation setup in WEBENCH (R) Designer for this device. As a workaround, you can use TINA-TI to simulate the same design. This is a free simulator that we provide and can be downloaded form here: http://www.ti.com/tool/tina-ti.

I am attaching the LM5017 application schematic which has been adapted to use the LM5018 design from WEBENCH. The model for LM5017 and LM5018 are the same with the only difference being the current limit. While using LM5017 model as LM5018, just make sure that you do not load the device beyond the rating for LM5018. If you have PSPICE 15.7 or above, you can also use the LM5018 PSPICE model to simulate the same circuit (http://www.ti.com/product/lm5018#simulationmodels).

For your convenienve, I am attaching the LM5018 WEBENCH schematic in TINA-TI for you. Let me know if you have any questions regarding this model or the simulation.

1351.LM5018_from_LM5017.TSC

Best regards,

0 Ron Kolarovic over 12 years ago in reply to Nikhil Gupta (Product Folder Models)

Prodigy 70 points

Nikhil,

Thanks so much for the quick response. I will start the analysis but to be truthful it has been years since using Tina. Do you have an equivalent simulation for the load response so I can get this upa nd running quickly? Also, do you see this bug being corrected soon? I find Webench to be a fast way to get the design initially checked out.

Thanks again...Ron

0 Nikhil Gupta (Product Folder Models) over 12 years ago in reply to Ron Kolarovic

TI__Mastermind 39210 points

Hi Ron,

I am attaching the modified schematic to simulate the Load Transient Condition. It has been setup for a load transient from 10mA to 250mA and back to 10mA. You can change these by changing RLOAD and ILOAD.

8078.1351.LM5018_from_LM5017.TSC

I will talk to my colleagues regarding the bug and see how soon it can be fixed.

Best regards,

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LM5018 SIM does not match input requirements