OP wanted also seconds in the result, so I assume he wants to give a non integer number as minutes (like 120,75 minutes)
This is what I'd do:
1. Take a decimal number representing Minutes (and fractions)
2. Convert to "Ticks" = 100 nano seconds
3. Initialize TimeSpan with calculated ticks.
4. Convert to desired output format (ToString)
Here is a little Testapp:
using System;
namespace MinutesToDateTime
{
class Program
{
static void Main(string[] args)
{
double dMinutes = 120.75d;
long iTicks = (long) (dMinutes * 60d * 10000000d);
TimeSpan ts = new TimeSpan(iTicks);
Console.WriteLine(ts.ToString("G"));
Console.ReadKey();
}
}
}