Equivalent Circuit and Application of Schottky Diode

Equivalent Circuit and Application of Schottky Diode

The main application areas of Schottky diodes are switching power supplies or SMPS, with operating frequencies exceeding 20 kHz.

Typically, the rated forward voltage of a 50 A Schottky diode at room temperature is 0.6 V, with a recovery time of 10 ns, designed specifically for SMPS applications. On the other hand, under the same current specifications, ordinary p-n junction diodes may exhibit a forward voltage drop of 1.1 V and a recovery rate of approximately 30 to 50 ns.

You may find that the forward voltage difference mentioned above is very small, but if we look at the power consumption level between the two: P (hot carrier)=0.6 x 50=30 watts, P (p-n)=1.1 x 50=55 watts, this is a considerable measurable difference that may seriously impair the efficiency of the SMPS.

Although the dissipation of Schottky diodes may be slightly higher in the reverse bias region, the net forward and reverse bias dissipation will still be much better than that of p-n junction diodes.

Reverse recovery time

In ordinary p-n semiconductor diodes, the reverse recovery time (trr) is very high due to the injected minority carriers.

In Schottky diodes, due to the extremely low minority charge carriers, the reverse recovery time is very short. That's why Schottky diodes can work so effectively even at frequencies of 20 GHz, which requires devices to switch at extremely fast speeds.

For frequencies higher than this, point contact diodes or crystal diodes are still used because their junction area or point junction area is very small.

Application of Schottky diodes

Schottky diodes have many applications. Of course, it can be used as a universal rectifier. However, due to its fast switching time and high-frequency capability, it is very advantageous for RF applications.

They are also excellent RF detectors because they can pick up signals that traditional PN junctions cannot pick up due to their low capacitance and forward voltage loss.

As mentioned earlier, Schottky diodes have high current density and low forward voltage drop.

Therefore, Schottky diodes are commonly used in power supplies. These diodes can reduce power loss and improve power efficiency.

In addition, due to improved efficiency, lower heat dissipation is required, which may allow designers to use smaller heat sinks in their designs.

When the transistor is forcefully turned on to generate a low level or logic "0" output, the base collector junction of the diode is forward biased. Schottky diodes absorb most of the current during operation, significantly reducing the turn off time of transistors and accelerating circuit speed.

In addition, Schottky diodes are essential components in various other devices, such as metal semiconductor field-effect transistors and photodiodes (MESFETs). This diode is not only widely used in various applications, but also serves as a key component in various other devices.