UC3843A: UC3843

Tool/software:

Dear Sir,

I want to design a buck converter Rating of 

Input= 55-80 V DC

Output= 50V,10A

with IC UC3843 at a switching frequency of 51Khz.

Mosfet used is Rm150N100 with gate on res.= 7.9ohm & gate off resistance =5.7ohm

Inductor =50uH

IN below image Ch1 yellow is gate pulse and Ch2 green is drain to source voltage.

please help to improve my gate pulse waveform 

this image is taken on input=60V and output is 50V 3A load.

Thanks and Regards