Un diode It is a two-terminal electronic device that allows the flow of electrical current in one direction while blocking the flow in the opposite direction. It works as a kind of electrical "valve" that allows current to flow in only one direction, from its anode (positive) terminal to its cathode (negative) terminal, and blocks current in the opposite direction.
The directly biased diode allows the flow of electrons through it, or what is exactly the same, allows the passage of electric current. In reverse polarization, it does not allow the passage of electrons through it.
Diodes have an electronic composition called PN Union, that is, they are the union of a semiconductor material called N with another called P.
Diodes are also known as rectifiers as they switch alternating current (AC) into pulsating direct current (DC). Diodes are classified according to their type, voltage, and current capacity.
Diodes have a polarity determined by an anode (positive terminal) and a cathode (negative terminal). Most diodes allow current to flow only when voltage is applied to the positive anode. Multiple diode configurations are shown on this graph:
By the time a diode lets a current flow, it is forward biased. When a diode is reverse biased, it acts as an insulator and does not allow current to flow.
the arrow of the diode symbol points in the opposite direction to the direction of the flow of electrons. Reason: Engineers conceived that the symbol and their schematics show current flowing from the positive (+) side of the voltage source to the negative (-) side. This is exactly the same convention that is used for semiconductor symbols that include arrows; the arrow points in the tolerated direction of "usual" flow and against the tolerated direction of electron flow.
The perfect diode test mode of a digital multimeter generates a small voltage across the test leads sufficient to apply forward bias to a diode junction. Normal voltage drop is 0.5 V to 0.8 V. The resistance of a good forward-biased diode should change from a thousand ohms to ten ohms. When reverse bias is applied, a DMM display shows OL (signaling very high resistance).
Current capacities are assigned to the diodes. If the capacity is exceeded and the diode fails, a short circuit can be generated by either) letting the current flow in both directions or b) interrupting the current flow in both directions.
Diode types
Sure, there are several types of diodes used in electronics for different purposes. Below I will provide you with a description of the most common types of diodes:
PN Junction Diode
This is the most common diode, and is composed of a PN junction, where a P-type region connects to an N-type region. It allows current to flow in one direction (forward direction) while blocking current in the opposite (reverse direction).
Zener diode
The Zener diode is a special type of PN junction diode designed to operate in the reverse breakdown region of its current-voltage characteristic. It is used to regulate voltage in electronic circuits.
Rectifier Diode
It is a semiconductor device used to convert alternating current (AC) to direct current (DC). Its main function is to allow the flow of electrical current in only one direction, blocking the flow in the opposite direction. This is essential for AC to DC conversion, as AC constantly changes polarity as it oscillates between its positive and negative cycles, while DC flows in a single, constant direction.
Schottky diode
This diode has a lower voltage drop than the typical PN junction diode, making it suitable for high frequency and fast rectification applications. It is characterized by its fast switching.
LED Diode (Light Emitting Diode)
Light-emitting diodes emit light when a voltage is applied to them in the forward direction. They are commonly used in displays, indicator lights and signaling lights.
Photodetector diode
This type of diode is used to convert light into an electrical signal. Photodiodes and phototransistors are examples of photodetectors.
Avalanche Diode (APD)
These diodes operate in the avalanche region and are commonly used in weak photon detection applications such as fiber optic photodetection.
Power Diode
Power diodes are designed to handle higher currents and voltages than standard diodes. They are used in power supplies, high power rectifiers and other high current applications.
Fast Switching Silicon Diode (FRS)
These diodes are designed for fast switching applications, such as in high frequency circuits and switching power supplies.
Tunnel Diode (DIAC)
The DIAC is a type of trigger diode used in phase control circuits and triac and discharge lamp lighting applications.
Surge Protection Diode (TVS)
These diodes are designed to protect circuits against transient surges and voltage spikes. They are commonly used in sensitive electronic circuit protection applications.
These are some of the most common types of diodes used in electronics. Each type of diode has specific characteristics that make them suitable for different applications. The choice of diode depends on the function it must perform in a circuit.
