What should one check Zfb,Zcs first, or missing leading edge blanking
block and one diode after fb input inside 0b2289?
(real ob2269 circuit has different component values and in addition
resistor divider at MOS gate and one more diode+capacitor in front of
VDD)
http://www.dianyuan.com/bbs/u/36/1135072817.pdf
http://www.leadtrend.com.tw/pdf/LD7552-DS-00.pdf
http://pdf1.alldatasheet.com/datasheet-pdf/view/103294/ETC/SG6841.html