Exploring Different Types of Diodes and Their Functions in Electronics

In electronics, there are particular components that play a critical role in circuitry. Without them, the device would experience short-circuiting. This is in the case of the use of diodes known as rectifiers. That means there are several types of diodes and functions. In this article, we explore the common types and what purpose they serve in an electronic device. 

What is a Diode?

Essentially, diodes are electronic components that allow current to flow in one direction. In other words, they are unidirectional current gates. They have two terminals —  a positive known as anode and a negative known as cathode.

Think of a diode as a switch that closes when the positive terminal comes into contact with a voltage that is higher than the negative terminal. Conversely, this switch opens when the anode is connected to a lower voltage than the cathode. In electronics, this is known as forward bias, and it is what facilitates the flow of current in a device. 

On the contrary, reverse bias also happens when the positive terminal receives a lower voltage than the cathode. In such instances, the diode kicks in and blocks the flow of current to the device, a function that is crucial in controlling the flow of current.

Types and Functions of Diodes

Diodes can be formulated in many configurations, with different features and characteristics. Let us explore some of the common ones.

P-N Junction Diodes

This is a broader category of diodes that represent several types of diodes. They are also known to be the simplest types of diodes.

A P-N junction diode can be thought of as a semiconductor device. It is made of a material such as germanium or silicon. P-N junction diodes have a P and an N-type region. The P region carries the positive charge while the N carries the negative charge. The two regions meet at a boundary known as the P-N junction, hence the name.

The flow of current or the lack of flow in this type of diode is controlled by the concepts we discussed earlier known as forward and reverse biasing. In this regard, forward biasing facilitates the movement of electrons from the P and N regions towards the junction; which then closes it. This means that the current is flowing and the diode can function as expected.

Light Emitting Diode (LED)

LEDs are the most common types of P-N junction diodes. They are semiconductor devices that emit light when current flows through them. This emission of light by an LED happens in the forward bias only. LEDs emit light depending on the type of semiconductor material it is made of and the wavelength of light.

Photodiode

This is another common type of P-N junction diode. It works in a similar fashion as an LED where it emits light when electric current flows through it. Its semiconductor material is highly sensitive to photons, or light electrons. The only difference between photodiodes and LEDs is that photodiodes rely on reverse biasing to emit light. 

Solar Cell

A solar cell is a type of P-N junction diode that converts light into electrical energy. The semiconductor material that makes up the solar cell is sensitive to light photons, something it has in common with a photodiode. 

Zener Diode

In this type of P-N junction diode, electric current flows in either a forward or backward direction when it reaches a predetermined level. They are also known as breakdown diodes. 

These diodes are named based on a voltage known as Zener voltage. The P-N junction on a Zener diode has a thin depletion region. This means that the distance between the P and N regions is smaller compared to other diodes.

Tunnel Diode

These types of diodes are known to facilitate conductivity at a higher-than-normal rate in forward biasing. Tunnel diodes also have a significantly small depletion region like zener diodes. The mechanism of the flow of current in forward and reverse biasing is similar to other diodes. However, they have one unique feature known as negative resistance that limits current flow when the voltage passing through is above a set level.

Avalanche diode

Current in avalanche diodes flows in reverse rather than in forward direction. This is in the case of high-voltage exposure. It has a relatively wide depletion region. This allows it to withstand high voltage in reverse flow. You will find avalanche diodes in applications such as microwaves and specific types of generators.

Functions of Diodes

Let us discuss some of the common functions of diodes in electronics. 

Regulate the flow of electricity

The regulation of electricity flow happens when the diode ensures that current flows are unidirectional. Also, this means that the diodes ensure that unwanted voltage does not invade restricted areas in a circuit. One of the best examples here is where diodes help prevent current from flowing back to a solar panel. 

Maintain constant voltage

Constant voltage can be beneficial in applications where the amount of voltage required is critical. For instance, some devices especially in the medical field can cause catastrophic damage in case of voltage fluctuations. Zener diodes are mostly used for this purpose due to their predetermined level of voltage that facilitates the backward or forward flow.

Convert AC to DC

Alternating current (AC) and direct current (DC) are different types of currents. AC needs to be connected to DC for storage purposes. This conversion happens with the help of diodes. In particular, diodes correct the AC waveform for the conversion to occur. 

In simple terms, correcting the AC waveform means that the diodes stop the current from the back-and-forth flow that is characteristic of an AC to a unidirectional flow that is characteristic of a DC.

Prevent Electrical Damage

If there were no diodes in an electronic device, it would keep experiencing malfunctions that come with electrical surges and fluctuations. Other common results of unregulated voltage include over-current and over-voltage. Diodes prevent these issues by diverting the flow of current or stopping it completely.

Advantages of Diodes

Some of the obvious benefits of diodes include;

Quick Switching

The time it takes for a diode to switch or facilitate the flow of current cannot be measured with standard units of measure. This time can go as low as picoseconds, which is blazingly fast. The advantage of this is that diodes can be used in applications where high frequency is required. For instance, in radio and microwave devices.

High Energy Efficiency

While they need energy to function, this energy is insignificant compared to how other devices use energy. This makes diodes quite energy efficient. A good example would be the LED which consumes practically 5 volts and produces a large amount of lumens. This contributes to high energy savings and prevents risks associated with high current flow. 

Can Regulate Voltage

The regulation of voltage by diodes happens in cases where there is a limit needed. For instance, some devices cannot handle high voltage since their components can be destroyed. In these cases, diodes ensure that the current flow is capped at a specific voltage to avoid these happenings.

Diodes have kept many devices from spoiling from voltage spikes that are common in many electricity sources. This is beneficial because a small device can help protect a large device such as a microwave or a television set. 

Have a Long Lifespan

A diode is one of those components in the electronic device that will not age or become spoilt easily. These devices have the structural integrity required to sustain all kinds of risky situations on the circuit board. This explains why diodes remain unchanged in a device while other components experience constant repairs and replacements.

Disadvantages of Diodes

On the other hand, diodes have some setbacks, but not as many as the benefits. Let us look at some of them.

Sensitive to Heat

Heat sensitivity is a common issue with diodes. High heat damages the core structure of these devices, which ultimately impacts their performance negatively. To avoid this, the device using the diode needs to have a cooling mechanism that ensures that the diode does not come into contact with excess heat. Diodes experience thermal runways which causes them to explode.

Prone to Damage by Current Overload

While diodes are meant to be the first contact of electric current, sometimes they can be destroyed by this current if it is too much. Current overload or overcurrent leads to short-circuiting, a common phenomenon in circuits. 

Some types of diodes have low forward resistance. Low forward resistance results in high power generation that can cause damage to the diode. Resistors are used in such instances to prevent such instances.

Cannot Withstand a High Reverse Voltage

A high reverse voltage means that the amount of voltage flowing in the opposite direction of regular flow is higher than normal. The problem with this is that the diode can experience leaking or failure. The results of this occurrence are the same as the overcurrent we discussed in the previous disadvantage. 

Conclusion

From this article, it is clear that devices and electronic gadgets would never function properly — at least for long — without diodes. They are among the most crucial components in a circuit. Therefore, as you use your devices, remember that diodes play a critical role in ensuring they are functioning optimally at all times.

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