One, The role of diodes

1. Zener diode

Zener diodes, sometimes called Zener diodes. The principle is to use the reverse breakdown state of the pn junction, the current changes in a wide range but the voltage remains basically unchanged. Zener diodes are graded by their breakdown voltage. If you want to get a higher voltage, you can use them in series, which can get a higher output constant voltage. For example, 1N4620 voltage regulator 3.3V, 1N4625 voltage regulator 5.1V, etc., the power ranges from 200mW to 100W.

2. Light Emitting Diodes

It is made of compounds containing gallium (Ga), arsenic (As), and phosphorus (P). GaAs diodes emit red light, silicon carbide diodes emit yellow light, etc. This diode is forward driven, with low operating voltage and relatively small current, especially for patch type, long life, light of various colors, widely used in billboards and digital screen displays and other needs Glowing occasions.

3. Diode for detection

Detection is to take out the modulation signal from the input signal, and take the size of the rectified current, generally 100mA as the dividing 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.

4. Schottky diode

A Schottky diode is a low-power, ultra-high-speed diode. Its main feature is that the reverse recovery time is extremely short, the minimum can reach several nS, and its forward voltage drop is only about 0.4V. Widely used for high current rectifier diodes, freewheeling diodes and protection diodes. Some switching power supplies require the use of Schottky diodes.

Second, the working principle of the diode

The diode is a pn junction formed by a p-type semiconductor and an n-type semiconductor. A space charge layer is formed on both sides of the interface, and a self-built electric field is built. When there is no applied voltage, because the carrier concentration on both sides of the pn junction is The diffusion current caused by the difference and the drift current caused by the self-built electric field are equal and are in an electrical equilibrium state.

When a forward voltage bias is generated, the mutual suppression of the external electric field and the self-built electric field increases the diffusion current of carriers and causes forward current (that is, the reason for conduction). When a reverse voltage bias is generated, the external electric field and the self-built electric field are further strengthened, forming a reverse saturation current I0 independent of the reverse bias voltage value in a certain reverse voltage range (this is also the reason for non-conductivity).

Semiconductor diodes are used in almost all electronic circuits. The use of semiconductor diodes in circuits can protect the circuit and prolong the life of the circuit. The development of semiconductor diodes has made integrated circuits more optimized and played an active role in various fields.

The most common function of a diode is to allow current to flow in only one direction (called forward bias) and block it in the reverse direction (called reverse bias). Therefore, diodes can be thought of as electronic versions of check valves. In practice, however, diodes do not exhibit such perfect on and off directionality, but rather more complex nonlinear electronic characteristics - which are determined by the specific type of diode technology. In addition to being used as a switch, diodes have many other functions.

The above is the role and working principle of the diode to share, I hope to help everyone.