Document Questions

Donglun Li

Other Parts Discussed in Thread: LM5118

The value of BBM-DCM losses in Page 35 of the key document can not be calculated. (TI-PMLK Buck-Boost Experiment Board using LM5118)

over 6 years ago

0 Minqiu Xie over 6 years ago

TI__Mastermind 21565 points

Hi Donglun:
I'm sorry that I couldn't get your point. May you share the detail description?

0 Donglun Li over 6 years ago in reply to Minqiu Xie

Prodigy 180 points

There is a table in page35. The value of BBM-DCM mode can not be calculated by the given formula. like the Ipkbb

0 Minqiu Xie over 6 years ago in reply to Donglun Li

TI__Mastermind 21565 points

Hi Donglun:
You need to understand the relationship among Ipkbb, Ivlbb,ILbb,and ΔIL. And in this case, the Ipkbb=ΔIL.

0 Donglun Li over 6 years ago in reply to Minqiu Xie

Prodigy 180 points

yeah. But there is also no formula for ΔIL. It just can be measured in the experiment. Because the given table in the following page, it has the results for theory as well as experiment. If the basic document is not completed, i can not calculated the value. Do you know how can I assess the whole theory background.

0 Donglun Li over 6 years ago in reply to Minqiu Xie

Prodigy 180 points

And also the formula for the BM-DCM and BBM-DCM in inductor conduction are the same. Should it be Ipkbb for the BBM-DCM mode?

0 Minqiu Xie over 6 years ago in reply to Donglun Li

TI__Mastermind 21565 points

Hi Donglun:
Thanks for your notice. I think you're right~I will check with my colleagues.
For the basic theory learning, there are too much material. I'm not known what you prefer clearly. So you could visit TI.com for training materials. https://training.ti.com/

0 Donglun Li over 6 years ago in reply to Minqiu Xie

Prodigy 180 points

Cheers!

0 Donglun Li over 6 years ago in reply to Minqiu Xie

Prodigy 180 points

sorry, do you have any results after checking?

0 Minqiu Xie over 6 years ago in reply to Donglun Li

TI__Mastermind 21565 points

Hi Donglun:
Thanks for your patient waiting~It should be Ipkbb for the BBM-DCM mode. You could visit TI.com for more training materials. https://training.ti.com/
Or you could buy some classic books about the switch power for theory background learning.

0 Donglun Li over 6 years ago in reply to Minqiu Xie

Prodigy 180 points

I have spent some time to find the formula for Ipkbb in the BBM-DCM mode in training materials, but can not find it . Could you give me the formula to calculate the Ipkbb?

0 Donglun Li over 6 years ago in reply to Minqiu Xie

Prodigy 180 points

if i use Ipkbb= i (lbb)+ΔIbb/2 to substitute in i(lbb)=1/2.Ipkbb(Ddmbb+D2dmbb), there will be two values of Ipkbb which will result in two different losses values.

0 Minqiu Xie over 6 years ago in reply to Donglun Li

TI__Mastermind 21565 points

Hi Donglun:
Ipkbb=Δ ibb in BBM-DCM.

0 Donglun Li over 6 years ago in reply to Minqiu Xie

Prodigy 180 points

Dear Minqiu:

May I ask another question? It is about the experiment 3. It says if a DC ELECTRONIC LOAD with dynamic current mode capabilities is not available,you can adopt the feedback injection technique discussed in [6][7], to simplify load transient tests by using a TI-PMLK board as
dynamic load emulator. Then I go for [6]and[7],have a look through the articles. But I cannot do the same experiment of the Part2 application with LDO board? Is there more details for the applications?

Best regards
Donglun

0 Minqiu Xie over 6 years ago in reply to Donglun Li

TI__Mastermind 21565 points

Hi Donlun:
Long time no see. Sorry that your question is out of my radar.
May you open a new post with tag of LM5118? My teammate who more experienced with LM5118 will catch you. Thank you~

0 Donglun Li over 6 years ago in reply to Minqiu Xie

Prodigy 180 points

yeah, I will. Anyway, thank you so much!

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