TOP254EN Switch burning at power-up!

Posted by: flapierre on 12/03/2008

Hi, I'm using a TOP254EN switch for a power supply, and I'm able to generate a perfect 12VDC. However, I have a major problem with that design since, not at the initial power-up but at the second power-up, the switch burns and smoke is coming out of it. I replace the switch, it works well at first power up, but then burns again at second power-up. My schematic is exactly as proposed using the Power Integration PIExpert design tool and application notes. Can someone please help me6 Does somebody experienced the same problem in the past? Thank you very much and best regards, Frank Lapierre

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Hi,

This behavior is not normal. Please send us a copy of your schematic, transformer design and PCB design to help us understand your problem.

Please attach any files in either PDF, TIF, BMP of JPG format.

Regards

PI-Sarek

Thanks for your support. I attached my schematic. I just noticed that my line sense resistor is a SMT 0603 package. Do you think that it could be a cause? Also, I do not have transformer desing and PCB informations with me at the moment. If you definitely need that information, please tell me and I should be able to have it soon. Thank you very much and best regards! Frank

Just to give you my latest observations, when I remove the input choke and byoass it, the problem is not there anymore, but I do not have a good, it is not regulated. Thank you very much! Frank

Hi, It seems like placing the choke before the bridge is the solution, since it solves the problem. Could you please explain me why the choke was placed after the bridge with PI Expert? Thank you very much and best regards, Frank