How to Design an RCD Snubber (a.k.a. RCD Clamp)

[@UmerAltaf89]

Nice to see you with a nice topic

[@SteveHobbyLab]

Zach - Nice job detailing the RCD snubber/clamp circuit design process. Yours is one of the best explanations I've ever seen. I'm curious what guidance you suggest regarding the minimum reverse voltage of the diode. I understand that the minimum reverse voltage of the diode is greater or equal to V-in. Although in my limited experience a non-clamped ringing can easily exceed V-in. Thanks.

[@Zachariah-Peterson]

That is true non-clamped ringing can exceed that value, and of course you can always select a bigger diode, unfortunately you have to deal with that switching time. Another option is use an RC snubber with the RCD clamp, the RC snubber attempts to counteract the resonance and take it closer to the critically damped regime. You can do that and get close enough to critical damping that you reduce the oscillation amplitude, and then the RCD clamp can dissipate the remaining power.

[@SanjaySharma-pw6ww]

thanks for sharing your knowledge. its a nice video on snubber.

[@djordjeblesic]

Great video, keep it up!

[@Mohammad-kj6hu]

How do we can reduce the voltage stress across the switch a part from clamp circuit in boost converter do you have any reference that could help me? Tnx

[@Zachariah-Peterson]

Another option is to put an RC circuit from the switch node to ground. This is also called a snubber and it would be used to set the oscillation such that it will be closer to critically damped. Doing this requires a measurement of the switching node ringing, and the process in a buck or boost converter is the same as that used in a flyback converter.

[@RedbeardtheEngineer]

This was informative thank you.

[@presleyuche4360]

GOOD ONE PROF, WHEN PWM IS WORKING WHAT PREVENT THE DIODE GETTING INTO OPERATION.

[@Владислав-т6е8м]

Why does L bias impact to the noise? If it is in series with a much bigger value of Transformer ?

[@leeslevin7602]

Brilliant, thank you. 👏

[@thenextproblem8001]

Yes! Finally🎉

[@royperkins28]

excellent video

[@garyh8093]

Well done!

[@ironchefhan1386]

thanks for your video, but I have a question about Isn current. Does it go to high potential?

[@ironchefhan1386]

sorry I just realize it is AC.

[@Zachariah-Peterson]

​ @ironchefhan1386 That's correct it is AC, so there is some phase difference between them due to the reactance in the circuit.

[@oksourav]

Love you Sir 😍

[@michaeld9682]

Nice description

[@AltiumAcademy]

Thank ya 😉

[@stevew9945]

Most interesting

[@mrlazda]

To be correct, flyback converters do not have transformer, they have coupled inductors.

[@Zachariah-Peterson]

Then I guess companies like Wurth and Pulse should stop calling their magnetics "flyback transformers"

[@mrlazda]

@Zachariah-Peterson they call it "flyback transformer," not transformer, and that is the name that is used to shoe itention (isolation). By the definition, transformers do not store energy, so that in flyback converter is not transformer. By the way, in all books and papers about SMPS, they stricky point that difference (chak any pape or book from accomplished authors in power ectronucs, for example Ben-Yaakov, Maksimovic, Cuk, Ridley, Vorperian, Middlebrook)

[@Zachariah-Peterson]

@@mrlazda Yes calling it a flyback transformer is still a term intending to show intention, but highlighting the difference with respect to coupled inductors is just splitting hairs. All transformers are coupled inductors but not all coupled inductors are transformers, depends how they are hooked up and driven and how the leakage interacts with the rest of the circuitry. For the RCD clamp or an RC snubber in a flyback converter it's a non-issue, the leakage inductance is what matters for the purposes I outlined here. Also I'm familiar with Ridley and Cuk, in fact Ridley makes very little distinction between coupled inductor and transformer in relation to flyback transformers in his video "Design, Build and Test a Flyback Transformer"

[@mrlazda]

@@Zachariah-Peterson every transformer is in pratice coupled inductor and every coupled inductor is "transformer", but when EE say transformer we asume device that do not store energy, have very high inductance of coils (idealy iinductance is infinity, lump model have infinity inductance). Both of that characteristics make them different then what is used in flyback converter, so that generally term used in flyback converter is coupled inductor (or you can call it flyback transformer, or ignition coil which is same as used in flyback converter but with different usage). I know that for Cuk (Ćuk) no one would ever heard if he called it transformer, that is easiest way on university he finish to get dreded sentence on exam "coleg you faild, see you next time", and I know that bacouse I finished same university as him only he finished much before me (same university finished only 10 yeard later, most citated name of all I mentioned Maksimovic(ć), his h-factor is over 90, he even worked on it as professor for short time). For me I find most easiest to follow are works by Shmuel Ben-Yaakov and Ray Ridley (I was even subscribed to his paer magazine when he was publishing it).

[@orhangunay3001]

hi