WEBENCH® Tools/LM5022: changing load for Bode plot simulation

Timothy Luca

Part Number: LM5022

Tool/software: WEBENCH® Design Tools

I want to get a Bode plot simulation under different load conditions. I'm designing a boost supply with 24V input and 100V/0.5A output. Webench runs the Bode plot with 200 ohm load - that's correct for 0.5A. But when I go to change to a lighter load, I get the input shown below which gives a min/max of 5/100 - it won't even let me put in the default value of 200. What's going on?

over 6 years ago

0 Youhao Xi over 6 years ago

TI__Guru* 78170 points

Hello Timothy,

Thank you for considering the LM5022. Did you attached something to your post? The link is broken. Could your re-attach?

Do you know the new Webench Power Designer tool? When you open the old Webench, and click the schematic icon, on top of the page it shows a link (Try it now) and you can use the new tool and just change the Iload and the tool allows you to re-simulate with the new load. You can change any parameter in the originally generated design.

Hope this helps.

Thanks,
Youhao Xi, Applications Engineering

0 Timothy Luca over 6 years ago in reply to Youhao Xi

Intellectual 790 points

The new Webench Power Designer had the exact same problem. I clicked on Iload, and nothing happened. I clicked on the Rload resistor which is 200 ohms. However, the listed minimum value was 5 ohms and the listed maximum value was 100 ohms - in other words, the nominal 200 ohms was not between the minimum and maximum. I wanted to change it to 500 ohms, but I could not.

0 Youhao Xi over 6 years ago in reply to Timothy Luca

TI__Guru* 78170 points

Hi Timothy,

I tried the new tool and the load is shown as a current source instead of the Rload resistor. I opened up the Webench design from the LM5022 product page (older Webench gateway), and once the design is created, I click the schematic, and on the upper left of the schematic window, it shows a link to the new Webench tool. Click that then the created design is transferred but the load changed to a current source. I can modify the current source as to change the load current. Can you try the same approach?

Thanks,
Youhao

0 Timothy Luca over 6 years ago in reply to Youhao Xi

Intellectual 790 points

Hi Youhao,

I'm sorry, but I followed your instructions and I don't get the same results you are getting. I've used the webench tool in the past with good success, so I do have some familiarity with it. I have repeatedly tried the new tool, and I get the same result from it. It also seems to take much longer for me to get a result with the new power bench.

I should also point out that the layout provided by the old webench doesn't make much sense - it puts two output capacitors on top of each other.

I'm going to attach two reports from the old webench.