Likewise, the off delay time is the sum of the storage time t, and the fall rime uf The storage time t, is the time interval it takes for the collector current to drop from 100% to 90% of its final value, during which the excess charge stored in the base is depleted. The greater the degree of saturation, the greater is the storage time. The fall rime yis the time interval it takes for the collector current to fall from 90% to 10% of its final value, The off delay time is