Part Number:UCC256301
according to our design resonance capacitor voltage peak is 515 volt and valley voltage is -115v . but the Vcr pin can take only positive voltage and its range is (upto 6 volt) so max voltage we can go is 400v considering 200v is common mode voltage corresponding to vcm (3v). so for higher primary rms current it is not possible to design vcr in specified design.