P6KE200A Clamp Diode blow up after sometime.

4 posts / 0 new

I am using LYT4227 IC to for my 36W Driver. I have made some of changes to work with indian power supply conditions.

My Driver Configuration are below.

Input Voltage : 180-300VAC (also can handle 450VAC without blowing fuse)
Output Voltage : 75V 440mA 33W
Efficiency : 87.5%
PF : 0.98

I have added following components to work with high input voltage(450VAC).

  • 3mH Drum Core after Bridge Rectifier
  • 5uF 900V Capacitor (2 x 10uF 400V) instead of 2.2uF 450V
  • Added 600V(2 x 1.5KE300A) zener protection across IC (Drain-Source Pin).
  • Also tested by giving two phase and 440VAC to Driver

I have measured temperature across P6KE200A and various parts none of them found suspicious.

Sometime P6KE200A(clamp diode across transformer primary winding) failed and start heating up. After some time it blows.

Is there any way I can stop blowing this clamp diode.


I have attached my circuit diagram.

첨부 파일Size
36W_LL - 74V 440mA ISO LYT4227.pixls43.5 KB
36W.jpg193.14 KB


Yes it happens - depends on your diode power dissipation , blocking voltage and amount of leakage inductance. If all of them are in the right range use a resistor to limit the current.
It works if not - look more carefully around your feedback!

Good luck.

"use a resistor to limit the current. "
is resister in parallel or series with P6KE200A. ?

I have seen that in some of design have put 2.2nF Cap and 390k resister to parallel of P6KE200A.


Before any change read data sheet to choose right amount for R11. it is important. 

You can use resistor in series with clamp diode to limit its current ( around 5 ohm ).

"I have seen that in some of design have put 2.2nF Cap and 390k resister to parallel of P6KE200A."

It's different - U also can use extra RC clamp in parallel with your blocking diode. it also helps to choose low power blocking diode. you even can remove blocking diode according to the data sheet but for some reason I still prefer to use blocking diode even when there is RC clamp.