LMR33630AP-Q1: Power management forum

Jimmy Gong

Expert 3600 points

Part Number: LMR33630AP-Q1
Other Parts Discussed in Thread: LMR33630, PSPICE-FOR-TI

Hi team,

I used Webench to simulate LMR33630 meet some issue.

step1, fill with spec customer request

step2,At schematic change component L1 to 6.8uH 44.6mOhm and Cout 22uF Qty=4

step3, run the startup simulate but Vout is almost 0. Vout should be 3.3V same as I setup at first time, is it right?

Did you have any idea why use webench tool will have this result?

BR,

Jimmy

over 2 years ago

0 Richard Fu22 over 2 years ago

TI__Mastermind 28070 points

Hi Jimmy,

Thanks for coming with this issue. Do you know if the waveform starts up normally if the schematic is not changed?

Regards,

Richard

0 Jimmy Gong over 2 years ago in reply to Richard Fu22

TI__Expert 3600 points

Hi Richard,

I only fill the spec customer request and run startup simulate(schematic is not changed). the result also wrong below.

BR,

Jimmy

0 Richard Fu22 over 2 years ago in reply to Jimmy Gong

TI__Mastermind 28070 points

Hi Jimmy,

Sorry my post did not come through yesterday. Let me take a look at this and I'll get back to you in a few days.

Regards,

Richard

0 Richard Fu22 over 2 years ago in reply to Richard Fu22

TI__Mastermind 28070 points

Hi Jimmy,

Depending on the device, it looks like you will get differing results due to the data provided when the Webench model is built. You may try using PSPICE-for-TI and simulating the results there.

Regards,

Richard

0 Jimmy Gong over 2 years ago in reply to Richard Fu22

TI__Expert 3600 points

Hi Richard,

thanks for your reply! Since this question is asked by customer, I would need to explain to them.

I'm not pretty understand. Do you mean that this model's Webench have some bugs need to be fixed and suggest to use Pspice for TI? or you follow my steps to use Webench and your result is correct and different from mine?

BR,

Jimmy

+1 Richard Fu22 over 2 years ago in reply to Jimmy Gong

TI__Mastermind 28070 points

Hi Jimmy,

I was able to replicate your result using your inputs.

What I meant is that the Webench model is based off of data provided for that specific device. Because of this, if not enough data is provided, accuracy can be limited. Therefore I suggest using PSPICE for TI, which should have the needed PSPICE model.

Regards,

Richard

0 Jimmy Gong over 2 years ago in reply to Richard Fu22

TI__Expert 3600 points

Richard,

Got it. thanks a lots!

So will someone fix webench?

0 Richard Fu22 over 2 years ago in reply to Jimmy Gong

TI__Mastermind 28070 points

Hi Jimmy,

It'll be on a list of things to update. For now, I recommend using PSPICE for TI.

Regards,

Richard