2W Pushpull needs primary snubber

[cupoftea]

Hi,
We are doing isolated pushpull of 2W, vin=5v, vout = ~-15V

We will use the SN6505x...

https://www.ti.com/lit/ds/symlink/sn6505a-q1.pdf?ts=1673785305891&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FSN6505A-Q1

Would you agree that the SN6505 application circuits shown in its datasheet would also need a Diode/TVS to be added to snub out the leakage inductance induced overvoltage?
The interneal FETs are only 16v rated, so would you agree, an 8V2 TVS/Zener and a diode should be connected from Vin to the drain of each internal transisfor?

 

[FvM]

Typically SN6505 works well without snubber as it's relative slow switching, primary waveform is almost trapezoidal.

 

[cupoftea]

Thanks, and i wonder if this is something to do with the fact that those Wuerth transformers that are suggested in the SN6505 datasheet, have extremely low leakage inductance? ...one wouldnt know, as none of their datasheets give the leakage inductance.

 

[stenzer]

Hi,

have a look at push-pull transformers from PULSE. They provide usually much more information than components from Wuerth, which are in my opinion always somewhat short of information (as least for me).

I can recommend the PH9185 series [1], which can handle power up to 3 W. The datasheet also states the leakage inductance.

[1] https://productfinder.pulseelectron...uct-attachments/datasheet_p708_1608184863.pdf

BR