to get into IIIT Hyderabad how much percentile is required for ECE under St category
I can’t say anything about marks as it depends on the paper. What you have to see is the percentile. Last year cutoff for IIITH CSE was around 99.9 percentile and for ECE it was around 99.8 percentile. Plan accordingly, if you want a 4 year course in IIITH. Alternatively, if you want a 5 year course, you have to write the UGEE examination.