LM5122: Transfer Function Control Block Diagram Question

Roy Chou1

Genius 16080 points

Part Number: LM5122

Hi Team,

I tried to draw the Transfer Function Control Block Diagram of LM5122.

May you let me know if my understanding is correct or not?

In addition, may you let me know the transfer function of PWM comparator?

And for slope compensation, it may impact the loop gain response. May you let me know if we could ignore slope compensation impact when we draw the bode plot? And why?

Thanks.

Roy

over 4 years ago

0 dehuan Qi over 4 years ago

TI__Intellectual 2775 points

Hi Roy

yes， I think the block is right. the error DC gain is 80dB.

It will affect the internal slope so it is not recommended to ignore.

You also can use the webench get the bode plot. the link as below.

www.ti.com/.../LM5122

0 Roy Chou1 over 4 years ago in reply to dehuan Qi

TI__Genius 16080 points

Hi Dehuan,

Could you let me know the meaning of error DC gain(80dB)?

For internal slope, how could we draw its bode plot? Is there any formula in Webench?

May you share the webench bode plot formula for internal used?

Regards,

Roy

0 dehuan Qi over 4 years ago in reply to Roy Chou1

TI__Intellectual 2775 points

Hi Roy

You talk about the transfer function of PWM comparator is means the DC gain？ Or other？

You can add it to the current waveform. Of course, it’s not easy.

I advise Webench maybe a more better choice.

unfortunately， we don’t have a formula to share.

Power management

Power management forum

LM5122: Transfer Function Control Block Diagram Question