400V high-side driver

You could try the IR2110(500v) or IR2113(600v) .They are both half bridge drivers,but you could use only the high side driver.I have used them in many apps.and have never had any issues with them.You will need to provide a 1000v ultra fast 1amp diode to bootstrap the bias capacitor (100nf).                                                                                                   

Good luck.

Thank you.

My pleasure.I thought about it later and if on and off time is not critical,you could use a photovoltaic isolator such as the VO1263 from Vishay.For 10 milliamps of input current into the leds in series,you can get 15 volts dc at 60 microamps from the outputs in parallel,which will fully enhance your power fet.Input/output isolation is 2500vrms.

Regards,neil f pattison.

VO1263 is good but it is  obsolete part.   ( farnell - No Longer Manufactured )

Sorry about that,Idid not know that it was obsolete.As usual,they made a big song and dance announcing its release a couple of years ago,but have not made any official announcement about its demise.Anyway,how many do you need?I have a couple of hundred I would be willing to sell.Or if you only need a couple,I could mail them to you for free.Your alternative is the PVI-1050 from International Rectifier.Compared with the VO1263 it is puny,but it will do the job.Hope this helps.Regards,Neil F.Pattison.

Thanks for your help.  the  PVI1050 is available. I think it's good for my design.

Regards,  Leshan R. Fernando