Turn - On Transient in a Diode

The turn-on transient in a diode is not as predominant as its turn-off process is, but nonetheless it affects the performance of the circuit in which it is placed. The circuit for simulating the turn-on transient process is shown in Fig.2 and the diode model used is the same as shown in Fig. 1.

In a practical circuit, it is often difficult to notice the turn-on transient process, for two reasons. Firstly, the turn-on process lasts only for a brief period. Secondly, the transient process of some other device can often mask the turn-on process of a diode. For example, the turn-off delay of the MOSFET can mask the turn-on process of the diode. The simulation, shown in the second applet, makes the assumption that the transistor is ideal and simulates the turn-on process in an approximate manner.

In some circuits, such as the flyback converter to be described in one of the pages to follow, the turn-on delay of the diode is crucial. The only practical remedy to address this problem is to connect an RC snubber circuit across the diode.

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APPLET FOR TURN-ON TRANSIENT IN A DIODE

 
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