Instead of a step, if a pulse is applied to the transistor switch, how does the device respond? To understand this, we consider the switching times of a transistor (see Fig. 6.24).
Let the input to the transistor switch be a pulse of duration T. When a pulse is applied, because of stray capacitances, collector current will not reach the steady-state value instantaneously. To know exactly when the device switches into the ON state and also into the OFF state, we define the following switching times of the transistor.
FIGURE 6.24 Switching times of the transistor