A closer Look to the Factors Affecting the Switching Transient Times of Optocouplers

Abstract

Abstract The significant parameters for high-speed optoelectronic switch were the transient times. In the time domain, there is a time elapsed in the order of microseconds between applying a current pulse and seeing an output. So, the present work aimed to give a closer look on the factors affecting the transient times of the optocoupler switching action, namely; delay (td)-, rise (tr)-, in addition to storage (ts)- and fall (tf)-times. The switching transient times of the optocoupler (type 4N25) were investigated and plotted under the influence of different operating conditions such as: load resistance (RL), forward LED drive current (IF), bias collector voltage (VCC), emitter-base resistance (RBE) and temperature. Experimental results showed that, the value of the turn-on time (Ton=td+tr) was decreased with increasing the following; IF and RBE, while it increased with increasing VCC and temperature as well, while it unaffected by increasing RL. On the other hand, the turn-off time value (Toff=ts+tf) was shown to be decreased with increasing VCC and RBE while its value increased with increasing the following; RL, IF and temperature.