hi i need to design circuit has 2 out put (-) one from 0 to -120 vdc and the other from 0 to -200 vdc and out power a bout 1 kw and the input to this circuit is dc
What is the source for the dc input power? What is the dc input voltage range (and is it regulated)? Does the output need to be isolated from the input?
A kilowatt is a lot of power, but that's only on the order of 5 A of current, so it shouldn't be too hard to design, except that those are higher voltages and that will probably greatly limit your choices due to component voltage ratings. You'll probably need to use some sort of switch-mode power supply topology. The specifics will depend on your input voltage.
Is the output voltage variable? Are you saying it is variable from zero to negative 120 V dc for one output, and from zero to negative 200 V dc for the other?
Hopefully someone with more switching converter experience can chime in with more info, but I do not think you will be able to find a dc-dc converter IC that will handle 240 V input. You may have to implement this converter from scratch, a very interesting but fairly involved project.