Schottky diode in electronic circuits

After the invention of the first semiconductor device, many great scientists have investigated the properties of the pn junction. As you may have guessed, this is an ordinary diode that can be seen in any electronic circuit. At the time of his invention, it was an element that produced a real revolution and changed all ideas about the future of electronics. Also, no attention was paid to the technology of its manufacture. There was a diode of Zenner and Gunn. Another was invented Schottky diode, Which has interesting properties. Its use in electronics was not as sensational as its famous "brethren". The special properties of this element were previously used in highly specialized schemes and were not widely used. The more interesting is that recently the Schottky diode has been used as the main element in impulse power supplies. It works in almost all electronic household devices: televisions, tape recorders, personal computers, laptops, etc.

The special properties of the device are manifested in a low voltage drop at the pn junction. It does not exceed 0.4 Volts. That is, according to this parameter, it is as close as possible to the ideal element, which is used in calculations. True, at a voltage of more than 50 volts these properties disappear. But nevertheless, the Schottky diode has become widely used in circuits with operational amplifiers. The power of such circuits did not exceed 15 Volts DC, which allowed to take full advantage of the properties of this device. He could stand in the feedback loop as a limiting element or participate in the work of regulators.

In addition to such an important property as the voltage drop across the pn junction, the Schottky diode has a small capacitance. This allows him to work in high-frequency circuits. Practically "ideal" properties of this element do not distort the signal of high frequency. That's why it was put into switching power supplies, communication devices and regulators.

But in addition to positive qualities, it is necessary to note the shortcomings. Schottky diodes are very sensitive even to a short-time excess of the reverse voltage from the permissible value. This leads to the failure of the element. Unlike its silicon "counterparts," it does not recover. Thermal breakdown leads either to the occurrence of leakage currents, or to the "transformation" of the device into a conductor.

The first malfunction will result in unstable operation of the entire electronic device. It is difficult to find and eliminate. With regard to thermal breakdown, then, for example, in a pulsed power supply, this will trigger a short circuit protection . After replacing the faulty element, the power supply will operate normally.

Modern industry produces quite powerful Schottky diodes. The impulse current in such devices can reach 1.2 kA. Constant operating current in some types reaches 120 A. Such devices have a wide current range and good performance characteristics. They are successfully used in household appliances and industrial electronics.