There are many types of diodes. It can be said that in addition to resistors and capacitors, there are more components. So what types of diodes are divided into?
1. Zener diode
Zener diode, sometimes called Zener diode. The principle is to use the pn junction reverse breakdown state, the current changes in a wide range but the voltage remains basically unchanged. Zener diodes are graded by breakdown voltage. If you want to get a higher voltage, you can use it in series, which can get a higher output constant voltage. For example, 1N4620 regulated 3.3V, 1N4625 regulated 5.1V, etc. The power varies from 200mW to 100W.
2. Light-emitting diodes
It is made of compounds containing gallium (Ga), arsenic (As) and phosphorus (P). Gallium arsenide diodes emit red light, and silicon carbide diodes emit yellow light. This kind of diode is forward driven, the working voltage is low, and the current is relatively small, especially for the patch type, long life, various colors of light, widely used in billboards, digital screen displays and other needs Glowing occasions.
3. Rectifier diode
It is conceivable that the rectifier diode is used for rectification, which uses unidirectional conduction to rectify AC into DC output. For the rectifier diodes in ordinary regulated power supplies, the reverse recovery time of the cut-off frequency is not very strict. Generally, the maximum rectified current and the maximum reverse working voltage are sufficient. Such rectifier diodes include 1NXX series, 2CZ series, etc. For high-frequency switching power supplies, rectifier diodes with higher operating frequency and shorter reverse recovery time are used. Such diodes include RU series, V series, 1SR series and so on. For higher ones, you can consider using Schottky diodes for rectification.
4. Diode for detection
Detection is to take out the modulated signal from the input signal, and take the size of the rectified current, generally 100mA as the demarcation point, usually the output current less than 100mA is called detection. Diodes for detection are usually used in small signal circuits such as semiconductor radios and televisions.
5. Schottky diode
The Schottky diode is a low-power, ultra-high-speed diode. Its main feature is that the reverse recovery time is extremely short, the smallest can reach a few nS, and its forward conduction voltage drop is only about 0.4V. It is generally used in large current rectifier diodes, freewheeling diodes, and protection diodes. Some switching power supplies require Schottky diodes.
The above five types are often used and are classified according to their use. In addition to these, there are: limiting diodes, modulation diodes, mixing diodes, amplifier diodes, switching diodes, varactor diodes, frequency multiplying diodes , PIN diodes, avalanche diodes, Ezaki diodes, fast turn-off diodes, damping diodes, transient voltage suppression diodes, double base diodes, etc.
In addition to classification according to use, there are classifications according to structure, such as point contact type, surface contact type, etc.; it can also be classified according to characteristics.
The functions of the diode are:
1. Rectification: Using the unidirectional conductivity of the diode, the alternating current with alternating directions can be transformed into a single-direction pulsed direct current
2. Switch: The diode has a small resistance under the action of a forward voltage and is in a conducting state, which is equivalent to a switched-on switch; under the action of a reverse voltage, the resistance is very large and is in a cut-off state, just like a disconnected one switch. Using the switching characteristics of diodes, various logic circuits can be formed.
3. Limiting: After the diode is turned on, its forward voltage drop basically remains unchanged (silicon tube is 0.7V, germanium tube is 0.3V). Using this feature, as a limiting element in the circuit, the signal amplitude can be limited within a certain range.
4. Freewheeling: It plays a role of freewheeling in the inductance of the switching power supply and inductive loads such as relays.
5. Detection: It plays a role of detection in the radio.
6. Variable capacity: used in the tuner of TV.
7. Display: used on VCD, DVD, calculator and other displays.
8. Voltage stabilization: The zener diode is essentially a junction silicon diode, and the zener diode works in a reverse breakdown state. In the manufacturing process of the diode, it has low-voltage breakdown characteristics. The reverse breakdown voltage of the Zener diode is constant, and a current-limiting resistor is connected in series in the voltage regulator circuit to make the current after the Zener diode breakdown does not exceed the allowable value, so the breakdown state can last for a long time without damage.
9. Trigger: Trigger diode, also known as bidirectional trigger diode (DIAC), is a two-terminal semiconductor device with three-layer structure and symmetry. It is often used to trigger triacs, and for overvoltage protection in circuits.
Extended information:
Among the diodes, electronic components, a device with two electrodes only allows current to flow in a single direction, and many uses are for its rectification function. The varactor diode is used as an electronic adjustable capacitor. The current directionality of most diodes is usually referred to as the "rectification" function. The most common function of a diode is to only allow current to pass in a single direction (called forward bias) and block in the reverse direction (called reverse bias). Therefore, the diode can be thought of as an electronic check valve.
Diode is one of the most commonly used electronic components. Its biggest feature is unidirectional conduction, that is, current can only flow in one direction of the diode. Second, use a multimeter to measure the reverse resistance if it is small. This diode is bad. If the reverse resistance is large, it means that the diode is good. For such basic components, the principle of action and basic circuit should be firmly grasped, so as to lay a good foundation for future electronic technology learning.
Reference link: Baidu Encyclopedia-Diode