<?php
$dbDate = '2017-11-27 20:00:00';
$dbDate = new DateTime($dbDate);
$aDate = new DateTime(date('Y-m-d H:i:s'));
$timePassed = $dbDate->diff($aDate);
$minutes  = $timePassed->days * 24 * 60;
$minutes += $timePassed->h * 60;
$minutes += $timePassed->i;
echo $minutes;