What is the fantasy world of diodes like?

I believe many people have seen a diode, so what is its function? For hardware engineers, the work is very boring. Only by finding their own fun in ordinary positions can they complete various tasks with full ability. . Today we are going to talk about the hardware engineer’s right-hand man, the diode. Let’s take a look around and see what skills there are~

Common types of diodes:

Diodes are widely used in hardware circuits. The main types of diodes include the following: Rectifier diodes: Using the unidirectional conductivity of diodes, alternating current alternating current can be converted into pulsating direct current in a single direction.

Zener diode: Made by utilizing the reverse breakdown characteristics (Zener breakdown) of the diode, the voltage at both ends of the diode remains basically unchanged in the circuit (at the critical breakdown point, the reverse resistance is reduced to a very small value , in this low-resistance area, the current is increasing, but the dynamic resistance is getting smaller, and the voltage is basically unchanged), which plays a role in stabilizing the voltage. Switching diode: Under the action of forward voltage, the resistance of the diode is very small and it is in the on state, which is equivalent to an on switch; under the action of reverse voltage, the resistance is very large and it is in the off state, like an off switch. .

TVS tube: similar to a Zener diode. Utilize the reverse breakdown characteristics (avalanche breakdown) of the diode.

Detector diode: similar to a rectifier diode. One-way conductivity is used to extract low-frequency signals or audio signals from high-frequency or medium-frequency radio signals. Limiting diode: After the diode is forward-conducted, its forward voltage drop remains basically unchanged (0.7V for silicon tubes and 0.3V for germanium tubes). Utilizing this characteristic, it can be used as an amplitude limiting element in the circuit to limit the signal amplitude within a certain range.

Light-emitting diode: After a forward voltage is applied to the diode, the holes injected from the P region to the N region and the electrons injected from the N region to the P region interact with the electrons in the N region and the holes in the P region respectively within a few microns near the PN junction. holes recombine, producing spontaneously emitted fluorescence. The energy states of electrons and holes in different semiconductor materials are different. The amount of energy released when electrons and holes recombine varies. The more energy released, the shorter the wavelength of the light emitted. The reverse breakdown voltage of a light-emitting diode is greater than 5 volts. Its forward volt-ampere characteristic curve is very steep, and a current-limiting resistor must be connected in series to control the current through the diode.

Photodiode: Photodiode works under the action of reverse voltage. When there is no light, the reverse current is extremely weak, which is called dark current; when there is light, the reverse current quickly increases to tens of microamps, which is called photocurrent. The greater the intensity of light, the greater the reverse current.

Schottky Barrier Diode (SBD): Schottky barrier diode uses the potential barrier generated by the contact between metal and semiconductor to play a unidirectional conductive role, while ordinary diodes use the unidirectional conductivity of PN junction. There are two disadvantages of Schottky diodes: first, the reverse withstand voltage is low, generally only about 100V; second, the reverse leakage current is large.

Fast Recovery Diode (FRD/SRD, Fast Recovery Diode): It is a semiconductor diode with good switching characteristics and short reverse recovery time. It is mainly used in electronic circuits such as switching power supplies, PWM pulse width modulators, and inverters. , used as a high-frequency rectifier diode, freewheeling diode or damping diode. The internal structure of the fast recovery diode is different from the ordinary PN junction diode. It is a PIN junction diode, that is, a base area I is added between the P-type silicon material and the N-type silicon material to form a PIN silicon wafer. Because the base area is very thin and the reverse recovery charge is very small, the reverse recovery time of the fast recovery diode is shorter, the forward voltage drop is lower, and the reverse breakdown voltage (withstand voltage value) is higher.

The above is a brief introduction to the classification of common diodes. There are many more classifications in actual use. They are used in different places and have different names. The above are some functions of diodes, I hope they can be helpful to everyone.