WEBENCH® Tools/LM25118-Q1: Stability of LM25118 , buck mode and buck-boost mode

Rana LM-S

Part Number: LM25118-Q1
Other Parts Discussed in Thread: LM25118,

Tool/software: WEBENCH® Design Tools

Dear TI Support,

I'm using the LM25118, I designed a custom design using WEBENCH Power Designer TOOL and extract the schematic file to Orcad.

In order to check the Gain Margin and Phase Margin in both Mode (buck mode and buck boost Mode).

My input voltage rage is : 6V - 18V

Output Voltage : 12V

Output current : 2.4 A

Firstly I need to know what's the input Voltage that i should using for each Mode?

secondly i have simulate the design with an AC inpute =14V, but I can't get the phase margin and the Gain margin?

Could you please check in the attachement my design and please let me Know what's the problem?

With Thanks and Regards,

Rana

over 6 years ago

0 Rana LM-S over 6 years ago

Prodigy 210 points

this is my WEBENCH design

webench_design_5033019_27_spb16_sim.xml

0 Rana LM-S over 6 years ago in reply to Rana LM-S

Prodigy 210 points

Kind Remembre

0 Amod Vaze over 6 years ago in reply to Rana LM-S

TI__Mastermind 21755 points

Hi Rana,

Sorry for the delay in replying.

I created the design with LM25118-Q1 in WEBENCH with your inputs, 6-18Vin, 12Vo, 2.4A Iout. I see that we have only enabled the bode plot simulation in the "charts" section. We do not support the bode plot sim under the "Sim" tab. How are you generating the AC simulation plot that you have attached in the post?

If you want to exercise all the modes (Buck or boost), then you can update the Vin under the "opvals" tab and hit "Recalculate". You should be able to see the operating values once you check the "All" radio button. You can check the values for Crossover frequency, gain/phase margin in that table. You can also observe the topology of operation depending on the Vin you pick by looking at the "Operating Topology" value.

Regards,
Amod

0 Rana LM-S over 6 years ago in reply to Amod Vaze

Prodigy 210 points

I simulate the webench custom designe in Orcad CIS

0 Amod Vaze over 6 years ago in reply to Rana LM-S

TI__Mastermind 21755 points

Under www.ti.com/.../toolssoftware I could not find the AC model that runs in PSPICE. I would recommend using the charts tab or opvals tab to get the loop response numbers in such cases.

Regards,
Amod

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WEBENCH® Tools/LM25118-Q1: Stability of LM25118 , buck mode and buck-boost mode