SMPS using UC3842 - And related problems

vantusaonho

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Re: SMPS using UC3842 - And related problems

« Reply #50 on: January 07, 2013, 02:22:37 14:22 »

I think it due to core saturation. Because with the same board, I tried with 110VAC, it work fine. But for 220VAC, it burned fuse and mosfet. Do you think same to me?


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vantusaonho

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Re: SMPS using UC3842 - And related problems

« Reply #51 on: January 09, 2013, 01:38:25 01:38 »

Job done Thanks All


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Faros

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Re: SMPS using UC3842 - And related problems

« Reply #52 on: January 09, 2013, 03:42:08 03:42 »

Quote from: vantusaonho on January 09, 2013, 01:38:25 01:38

Job done Thanks All

@vantusaonho
You owe members who tried to help you some explanation of "how your job is DONE?!!" , this way you may find someone answering your request next time.


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vantusaonho

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Re: SMPS using UC3842 - And related problems

« Reply #53 on: January 09, 2013, 11:53:38 11:53 »

Oh! I wind another transformer again with less than primary winding in turns. And note that with 220VAC, the DC voltage after rectifier will be 220*sprt(2) - 10% margin - 20V (ripple and drop diode voltage) = 260V. From that, the turns for primary winding will be decrease as a result.
More turns more flux flow. So core saturation will reach quickly and leading to smoke mosfet and fuse. That is real problem
I hope you get success as me.


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