title: PHP convert time into a Time Period
body: <p>There appears to be a lot of info converting a time period into a time, but not the other way around.</p>
  
  <p>An example of what I need to do, is convert say 120 minutes into P0DT2H0M0S.
  And 13:10 into P0DT13H10M0S.
  And 120 minutes into PT2H0M0S.</p>
  
  <p>Any quick and easy way to do this?</p>