One of my friends studied at REVA University. According to him, it is said to be more than 75%.

It is safer upto 60% if you have a valid reason for your absence and have a leaving certificate. But going through this is a lot of hassle. This would require the involvement of the director or coordinator or mentor, etc. 

So to avoid such a hassle it is better to maintain 75%. Take leaves only if they are absolutely necessary.