Drain Pin of LNK6666E burning out

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Hi ,

When i had power up the board within fraction os seconds my drain pin of LNK6666E is burning out. What factors effects this and kindly let me know to debug and resolve my current issue.

I/p=195-265VAC

o/p=36V 1.5A

 

Regards,

Kranthi,

Hi Kranthi,

 

Good day and thank you very much for considering PI products particularly LNK6666E. Several factors like drain over voltage, current overload, cross conduction, and the like may affect the drain performance, or particularly the mosfet peformance resulting to failure. Now to resolve such issue, we would suggest if you can provide some schematic and captured waveforms to start with. You may also verify if the transformer is properly constructed. By the way how many boards/units have you had this problem? Or is it only through one board? 

 

 

Hi Davinci,  

Kindly find attached schematic and let me know how we can debug this. I can take the plots as it was burning right immidiate after power up.

Regards,

Kranthi.

TitleSize
galaxy_ver4_36v_03082016_1.pdf17.64 KB

Hi Kranthi,

Looking at the schematic, we suppose all are fine. Now, one critical factor that must also be considered is the transformer contrruction. Have you verified such construction? Aside from the physical verification, it can also be check through looking at the waveform/s by injecting some pulses on the primary and see if the secondary voltage is in fact in the flyback mode. This can be done even with the transformer only. No need to power up the whole unit. By the way is there some waveforms captured during the power up stage? Particularly looking at the AC input, drain voltage and current, as well as secondary diode voltage. Kindly verify on these ones. Hope this helps.

 

 

 

 

 

Hi Davinci,

Can you explain indetail/procedure how to test transformer without powering whole unit such that i can send you plots because as of now am unable to take any plots as LNK6666E was burningout right immediately after powering-up. Also tested the input path and output path and they were working fine but when am using switching circuitry with transformer the system was failing.

 

Regards,

Kranthi.

Hi Davinci,

 

We had tested transformer on the original layout where its working fine. We are suspecting layout as we observed the difference in resistance with same values. Also can you check the layout? let me know in which format do you need them.

 

Regards,

Kranthi.

Hi Kranthi,

Then we suppose that the problem lies basically not on the LNK666E but probably on the layout itself. When you say that there is a difference in resistance, do you mean that the copper trace resistance of one board is different from the other one? As for the layout, first how many layers are you using? If you are using just a one or two layer layout you can just give a screenshot of both sides with circuit codes and from there that will be enough to see if you've correctly configured such layout for LNK666E.

 

Hello PI,
I m using LNK6666E . i am facing many issues like board not working, when changing the LNK with that same board its working fine and burning issues both are continuously happening. what needs to be tested

Your D1 is the wrong way round... on the pcb ...

Hi aattral,

Can you share the schematic, PCB Layout, and PIxls design document as well as transformer construction document.

In future if you would like to post a question in the forum, please start a separate thread so that your post does not get mixed up with other forum questions.

Regards,
PI-NANO