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  1. #1
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    flyback + uc3842 + ripple output

    Hi, I have made one smps with this specification.
    Vout=100v to 1300v (variable), Iout=40 mA , Vin=22v - 30v (DC-2 Battery)
    Controller IC=UC3842 , Transformer=EE50-42 , gap=1mm , Lp=14 uH , Ls=85 mH , Ip=14A, Np=9 Ns=600 , Bmax=100 mT

    1-I have a ripple on output voltage!! its about 50 volt at 1300 volt
    2-I have a sin wave on drain of mosfet when the mosfet turns off !!!
    3-I have a loud audio from transformer!!

    first I put 22 nF at output and it has some audio noise , after I put 220 nF at output and audio noise had gone but voltage ripple get larger!! I put the schematic of this circuit here. please help me to improve this.

    http://www.4shared.com/file/22226330...ic_Prints.html[/url]

    its the picture of sin wave at drain of mosfet in dcm operation.

    http://www.4shared.com/file/22227578...2/snubber.html

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  2. #2
    Full Member level 5
    Points: 3,930, Level: 14

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    Re: flyback + uc3842 + ripple output

    Is there any body to help me,please?

    I add one resistor from feedback to pin 2 of 3842 and it was better.

    please help me.



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