What can be used instead of Zener in a flyback Diode-Zener snubber ?

[eem2am]

Hello,

I am doing a 230VAC , offline, 10W flyback, discontinuous mode.
Vout = 30V

I wish to use an RCD snubber on the primary:

But what should I use for the “D” of the “RCD” ?

Should it be a ……….

1. Zener,
2. Zener TVS,
3. TVS,
4. Transzorb,
5. MOV

?

 

[Tahmid]

Flyback RCD snubber

Hi,
The D has to be an ultrafast high voltage diode.
Some diodes you can use:
BYV26E, UF4007, UF5408, BYT43J

Hope this helps.
Tahmid.

Added after 2 minutes:

Sometimes, along with RCD, a transzorb/transil/transient suppressing diode is placed, although this is not absolutely necessary. An example of TVS is P6KE350 (350V, 600W) or P15KE350 (350V, 1500W).

 

[eem2am]

Flyback RCD snubber

i must apologise profusely.

I meant a Diode-Zener type snubber,

My brain defaulted to "RCD" snubber becasue thats what i am familiar with

...and i wonder about what would might be used in place of the zener, and why?

eg, TVS, transil, MOV, transzorb etc

 

[Tahmid]

Flyback RCD snubber

Hi,
For diode-zener, the diode must be ultrafast high voltage diode, like I stated above.
The "zener" has to be a TVS. Transil/Transzorb/TVS are really the same thing. Like I stated above, you could use the P6KE or P15KE series as this is what I had success with.
P6KE350 or P6KE400 would be your way as this clips the rail to the required voltage and has a surge capability of 600W (more than enough for your application), there'd be no reason to go to P15KE.

However, when you go to high power application, only TVS will not do, and you have to have an RCD-TVS snubber.

Hope this helps.
Tahmid.

 

[eem2am]

Flyback RCD snubber

thankyou very much indeed Tahmid

I am glad you have cleared up that D-Zener snubber alone is only for low power.