How to PWM-drive a N-channel non-logic level power MOSFET with a 3.3V signal?
This answer was made before the OP decided to scrap his original circuit (following what I'd said) thus rendering part of my answer obsolete. The OP should consider that evolving his questions following advice in answers is problematic. Regards the new circuit drawn, it is full of mistakes and won't work effectively when those mistakes are corrected. Note to the OP - if you persist in evolving your question, don't expect any more help from me. Neither should you take it on yourself to edit my answer.

Original answer: -

Firstly, if the power supply can produce 200V then the IRF630 is a terrible choice - it's maximum voltage rating is only 200V and you need clearance - I'd go for a MOSFET with 300V ratings.

Secondly, the solution is best addressed by putting the MOSFET at the bottom of the chain of LEDs. Now its source connects to ground and driving from a 3V3 signal is easy except that the IRF630 won't be great at turning on with a 3V3 signal. It might work but, given its inadequate voltage rating I'd look for a better device. Here's what I'm thinking: -







simulate this circuit &ndash; Schematic created using CircuitLab

So try looking at Fairchild (for example) to find a suitable MOSFET