LM2596-ADJ simulation in Multisim or Webench

Egor Tamarin

Other Parts Discussed in Thread: LM2596

Hello!

I am currently tasked with assembling a buck converter based on the LM2596-ADJ IC. I want to simulate the circuit before I build it. However, neither Multisim nor Webench have the required IC and thus I can do nothing. No libraries were found by me either.

How can I simulate the LM2596-ADJ?

over 8 years ago

0 JohnTucker over 8 years ago

TI__Guru**** 191445 points

There are spice models for the fixed versions. The adjustable version is supported in webench. See this link:

www.ti.com/.../toolssoftware

0 Egor Tamarin over 8 years ago in reply to JohnTucker

Prodigy 110 points

I have found the ADJ in Webench, thanks. I still want to stimjulate the circuit somewhere else. Does LTspice have the adjustable model?

0 JohnTucker over 8 years ago in reply to Egor Tamarin

TI__Guru**** 191445 points

We do not support LTspice for obvious reasons I think. I don't directly support LM2596. Lets see what that product group can suggest.

0 JohnTucker over 8 years ago in reply to JohnTucker

TI__Guru**** 191445 points

Moving to the Simple Switcher forum...

0 Arief Hernadi over 8 years ago in reply to JohnTucker

TI__Mastermind 23845 points

Hi,

Yes you can simulate the ADJ version of the IC. You can try to enter maybe 8V on the condition and it will show you how to do with FB resistor

Thanks

-Arief

0 Egor Tamarin over 8 years ago in reply to Arief Hernadi

Prodigy 110 points

I have managed to fing the ADJ version in Webench. However the simulation gives me results that differ from the calculations suggested in the datasheet.

0 Arief Hernadi over 8 years ago in reply to Egor Tamarin

TI__Mastermind 23845 points

Hi Egor,

Do you know which parameter that is different? Sometime webench can be optimize on the footprint or efficiency so therefore there might be some slight difference in terms of inductor size and DCR.

Thanks
-Arief

0 Egor Tamarin over 8 years ago in reply to Arief Hernadi

Prodigy 110 points

Well, all of them are different, except for the resistor values. I calculate using the information on the datasheet.

For example, the output capacitor is 100uF while I have a value of 470uF (according to the datasheet, a 470uF cap value is needed for a 24V-5V converter that I'm building.). The inductor values differ twice: I have 68uH, again from the datasheet, WEBENCH offers me 120uH and no value even close to mine. I could go on.

The thing is though, when I turn the optimization knob, the adjustable version disappears from the list of available ICs...

0 Arief Hernadi over 8 years ago in reply to Egor Tamarin

TI__Mastermind 23845 points

Hi,

I try to put in your parameters from 24V to 5V on Webench and the power components (Inductor and capacitor) is close to what you calculated which is 68uH and 330uF.

See the attached design pdf file

webench_design_24V_5V.pdf

0 Egor Tamarin over 8 years ago in reply to Arief Hernadi

Prodigy 110 points

The values are closer now, that is good (however, you use a fixed output configuration while I use the adjustable version, and the output current should be 1A for me.). Why does WEBENCH give me the strange values then? It should base its calculations on the design procedure by TI, no?

Here's my deign report:

webench_design_4847578_14_28973069.pdf

0 Arief Hernadi over 8 years ago in reply to Egor Tamarin

TI__Mastermind 23845 points

Hi,

I think the reason for discrepancy is because you use the 27VIN as maximum value, the reason is because webench calculate the inductor based on max value of VIN and that is why you have a higher inductor value. If you put 24VIN then it will be closer to the value that you are getting from datasheet.
If you want to use the ADJ version instead of the fixed version, you can go to the
www.ti.com/.../overview.page

and you enter the parameters from the main page, then you will select the integrated option since this is an integrated buck IC. It will then give you several option of IC that might work for your design and you can pick which version of LM2596 or other IC that works for you

Thanks
-Arief

0 Egor Tamarin over 8 years ago in reply to Arief Hernadi

Prodigy 110 points

Thanks, Arief.

I managed to run a simulation in LTSpice (though it was not an official model), so far everything checks out. Thanks for your assistance.

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LM2596-ADJ simulation in Multisim or Webench