Constant on time control of PWM converters: An intuitive explanation

[@hasnainjahanzaibrajput9805]

Hello Professor, I would like to ask that how the min. Off time is set since we have COT so our frequency will not be fixed. Lets just say rhe converter reached the steady state and our frequency is 1 MHz. How do we set this min. Off time and in one of the picture that you have shown in the video there is a block of minimum off timer. How do we make it? Thanks

[@sambenyaakov]

A timer

[@ivanperezs]

Thank you, Professor Ben-Yaakov. I always learn something new in your videos.

[@sambenyaakov]

Thanks Iván

[@christonfredrick]

at 3:11, why is there a drop in the Vout when there is step increase in I?

[@sambenyaakov]

Due to the feedback loop BW limit and iductor's limited current slew rate

[@jffighting]

Thank you, Prof. Ben-Yaakov, very intuitive explanation for this constant on time control for buck converter. Do you know who is the first person to propose this constant on time or constant off time control for buck converter?

[@sambenyaakov]

No. Will be happy to find out.

[@jffighting]

@@sambenyaakov Thank you for your reply, Prof. Ben-Yaakov. I tried to find the first reference but not be able to make it. It seems that everyone took it for granted before 1990. But I found one patent from Infineon (US7521913B2) that they use output voltage to adjust the pulse width and frequency during load transient. The technique in this patent is very similar as the COT control during load step up. Will this claim still be valid?

[@sambenyaakov]

@@jffighting 🤔

[@ezranoam]

Hi professor Ben Yaakov and thanks for another great video. Can you please elaborate on the benefits of constant on time control compare to other controll schemes other than a simpler control system. When would this control system will be more attractive? What performance (efficiency, transient speed etc..) would this method have compare to other controll methods? Thanks for another great video, Noam

[@sambenyaakov]

Hi Noam, Thanks for comments from which I learned that I have met my objective of this video: arising interest and curiosity in subject😊. Considering the fact that retention time of videos is short (up to now for this video: Audience retention Since uploaded (lifetime) 5:44 (25.9%) Average view duration) long videos are not effective (for most viewers). I may have a follow up on this subject keeping in mind your wish list

[@ezranoam]

@@sambenyaakov yes I am intrigued! Thanks for the comment and for placing my request in the pile.

[@sambenyaakov]

Hi, Just posed your questions at www.linkedin.com/feed/update/urn:li:activity:6672198007666028545

[@gutony3151]

Awesome, thanks a lot.

[@sambenyaakov]

Thanks.

[@gnanaprasad9874]

Great!!! Thank you. Prof. Yaakov, Can you please do a video on controller working of multi phase buck converters?

[@sambenyaakov]

Have you watched this? kzbin.info/www/bejne/Z5rUXox3Z86ppdU

[@vinayupadhyay9422]

@@sambenyaakov Is there any video for Coupled Inductor Multiphase buck converter ?

[@dimitarnikolov3527]

Thanks, for the great video! I am wondering, is it's possible remove the output ripple with a capacitance multiplier after the feedback?

[@sambenyaakov]

Thanks for comment. Not sure I understand what you mean. If auxiliary ciruit is used, no need for ripple on output.

[@abhishekdwivedi556]

Indeed a good lecture.

[@sambenyaakov]

Thanks

[@SanjayPatil-ju7ch]

Hello Prof Ben-Yaakov, Thanks for an excellent video !! Question - In Constant On-Time architecture, will high/low side switching frequency be a function (linear) of output current IX after transient settle?

[@sambenyaakov]

Not of current. Depending on type of controller, it might be a function of voltage transfer ratio.

[@SanjayPatil-ju7ch]

@@sambenyaakov Thanks Question - Then what really changes in a controller to supply a larger current after transients have subsided say from 5 amp DC to 20 amp DC? Since on-time pulse width is always constant, I thought the number of high pulses (switching freq or off time) must be the only way to supply increased current demand.

[@sambenyaakov]

@@SanjayPatil-ju7ch See kzbin.info/www/bejne/j6K7aH19eJynkLM

[@souravrangnekar2347]

Thank you for lovely explanation!!!

[@sambenyaakov]

Thanks