bootstrap supplying for UC3843(forward convertor)

Discussion in 'Homework Help' started by saturnsakini, Oct 7, 2015.

  1. saturnsakini

    Thread Starter New Member

    Jul 10, 2015
    Hi everyone, i designed a forward converter with this spec
    Vinput= 50V-150V DC
    V output = 12V, 5A

    i used for control and feedback circuit uc3843 ic. when i make work convertor exactly, supplying uc3843 with external 15V dc source, converter and uc3843 works how my except. but i need a internal supply for uc3843. i read about that it possible with a bootstrap circuit and i tried it. i can make work it for 50V,which is my minimum input. but @150 input my convertor output is failing although i keept uc3843's supply 16 to 22V.( it's data sheet say it can work 10V to 30 V supply).

    @150V input("150V.png" file)
    Yelllow one is convertor output voltage,(about 1V)
    blue is convertor output current
    red is uc3843's supply

    @50V input ("50v.png" file)
    blue and yellow wave form is similar you can copmpare it y axis for voltage and y axis for amper)
    red is uc 3843 supply voltage.

    and u can see the all circuit in "circuit.png" file, if anyone want to check over, i can add ltspice simulate file.