What is the principle of rectifier diode substitution? What is the difference between Schottky diodes and Schottky diodes

What is the principle of rectifier diode substitution? What is the difference between Schottky diodes and Schottky diodes

With the rapid development of technology, our lives have become inseparable from various electronic products. As we all know, there are two types of electronic products commonly used in the production of electronic products: Schottky diodes and rectifier diodes. To help everyone gain a deeper understanding, this article will summarize knowledge related to electronics. If you are interested in the content that will be covered in this article, then continue reading.

What is a rectifier diode?

A semiconductor device that converts alternating current energy into direct current energy. Usually it contains a PN junction with two terminals, positive and negative. The important characteristic of a diode is its unidirectional conductivity. In a circuit, current can only flow in from the positive pole of a diode and out from the negative pole.

A rectifier diode utilizes the unidirectional conductivity of a PN junction to convert alternating current into pulsating direct current. The leakage current of rectifier diodes is relatively large, and most diodes are packaged with surface contact materials. In addition, besides the parameters mentioned earlier, the parameters of rectifier diodes also include rectifier current, which refers to the current value that the rectifier diode is allowed to pass through during long-term operation. It is the main parameter of rectifier diodes and the main basis for selecting rectifier diodes.

Principle of rectifier diode substitution

Power supplies have both low and high frequencies. For series stabilized power supplies, this is a type of power supply that continuously adjusts the voltage drop of the power transistor to obtain a stable output voltage when the input or output changes. This type of adjustment transistor operates in a linear amplification state, and this circuit does not require high reverse recovery time for the rectifier diode. Therefore, this type of power supply rectifier diode only needs to meet the maximum rectification current. Several principles can be considered for the replacement of rectifier diodes:

① A rectifier diode with a higher maximum average rectified current can replace a diode with a lower rectified current, but the opposite is not possible;

② A rectifier diode with a high reverse operating voltage can replace a rectifier diode with a low reverse voltage, but not the other way around;

③ A rectifier diode with a high operating frequency can replace a rectifier diode with a low operating frequency, but not vice versa.

Difference between rectifier diode and Schottky diode

Schottky diode is a fast recovery diode, which belongs to a low-power, ultra high speed semiconductor device. Its notable feature is that the reverse recovery time is extremely short (can be as small as a few nanoseconds), and the forward conduction voltage drop is only about 0.4V. Schottky diodes are commonly used as high-frequency, low-voltage, high current rectifying diodes, freewheeling diodes, protective diodes, and are also used as rectifying diodes and small signal detection diodes in microwave communication circuits. Commonly used in secondary power rectification and high-frequency power rectification of color TVs.

Schottky diodes use metal semiconductor interfaces as Schottky barriers to produce rectification effects, which is different from the P-N interface generated by semiconductor semiconductor interfaces in general diodes. The characteristics of Schottky barrier make the conduction voltage drop of Schottky diode lower and can improve the switching speed.

The conduction voltage of Schottky diodes is very low. A typical diode produces a voltage drop of about 0.7-1.7 volts when current flows through it, but the voltage drop of a Schottky diode is only 0.15-0.45 volts, which can improve the efficiency of the system.

The difference between Schottky diodes and general rectifier diodes lies in the reverse recovery time, which is the time required for the diode to switch from a conducting state with forward current to a non conducting state. The reverse recovery time of a typical rectifier diode is about several hundred nanoseconds, while for high-speed diodes it will be lower than one hundred nanoseconds. Schottky diodes do not have reverse recovery time, so the switching time of small signal Schottky diodes is about tens of pS, and the switching time of special large capacity Schottky diodes is only tens of pS. Due to the fact that rectifier diodes generally generate EMI noise during reverse recovery time due to reverse current. Schottky diodes can switch immediately without any issues with reverse recovery time or reverse current.