Switching diode – Limitations of Shottky

A switching diode is suitable for switching a tiny signal of as much as 100 mA, serving as a rectifier. On the other hand, a rectifier diode is utilized for AC line correction (from alternating current to direct current). Switching diodes are created to manage a voltage of less than tens of volts.

The Schottky Rectifier

Now, we require to go over the recovery features of the fast switching diode. In easiest terms, there are none! At least not if we specify reverse recovery as the moment it takes for the junction to be cleared of charge carriers– and also the deficiency zone re-established and also expanded.
Up to now, we have been reviewing the recovery qualities of the silicon PN joint rectifier. These recovery characteristics result from the physics of the PN semiconductor joint. The Schottky rectifier behavior, nonetheless, is not based on the PN joint. Instead, its capability to correct is based upon the Schottky barrier joint (often referred to as a metal-on-silicon joint).
Unlike the PN junction, the Schottky joint does not have a depletion area. Schottky rectifiers, therefore, can have regular trr values of 10ns or less for some modest-current devices. With Schottky rectifiers, the switching can basically be taken into consideration immediate, with the only hold-up being from the junction capacitance (which is normally little). And also since the percentage of recovery time they have is mostly because of capacitance, that recovery is soft as well as fast. 

Limitations of Schottky Rectifiers

If Schottky rectifiers are so uber fast as well as soft and also reduced VF, why aren’t they always the best choice? Well the solution, sadly, is that they are prone to self-destruction through thermal runaway if the power dissipation, heat-sinking, and operating temperature level conditions are not effectively considered. This is since their reverse leak enhances significantly with temperature.
A regular Schottky that has an Ir of 0.25 mA at 25 ° C will have that leak balloon to 30mA at 125 ° C– that’s even more than a factor-of-100 increase.

Nevertheless, a Schottky may be a good option under the following problems:
– if your VR demand is modest (i.e., just low voltages anticipated in the circuit).
– if you can tolerate some considerable leakage (and also the warmth that the VR × Ir product will certainly produce).
– if you are positive that you can sink away the warmth adequately to preserve a reduced operating temperature under all foreseeable problems.

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