February 1, 2023

The Difference between Zener Diode vs IC LM78xx in Voltage Regulator System

Electronic devices often require a consistent and stable amount of voltage in order to function properly. A voltage regulator is used to provide electronics with voltage stability and reliability. All the voltage from the power source goes to the voltage regulator. From there, the voltage regulator delivers a regulated amount of voltage to the electronic device.

The output voltage from the regulator is automated, based on certain feedback techniques related to the voltage demand of the electronic device. Sometimes you could have a simple voltage regulator like a Zener Diode or a more complex linear regulator like the IC LM78XX.  The purpose of the regulation is to enhance the efficiency, reliability and performance of the electronic device while keeping everything safe for the user.

The Zener Diode and IC LM78XX are both types of voltage regulators, but they work in different ways. Let’s discuss the main difference between the Zener Diode and IC LM78XX.

IC LM78XX

This is an integrated circuit linear regulator which represents a family of regulators. The XX represents the amount of output voltage to the electronic circuits or integrated circuits. For instance, if you have an IC LM7805 as the voltage regulator, then it has an output of 5 volts. If you have IC LM7812 as the voltage regulator, then it has an output of 12 volts.

A lot of electronics manufacturers love to use the IC LM78XX because it is cheaper to produce and easier to use. But because they have a low voltage output, they’re generally found in low-voltage systems that don’t require a lot of power. Linear regulators really serve as voltage divider circuits because they depend on voltage feedback to keep the output consistent and effective.

Unfortunately, there is a setback to linear voltage regulators. There is often a voltage drop by at least 2 volts on an IC LM78XX, especially if it is an LM7805. In other words, if you want to sustain 5 volts of output from the regulator, then it needs a minimum of 7 volts of input. If you end up sending more than 7 volts, such as 10 volts, then it’ll drop even more voltage. This would ultimately bring down the energy efficiency that it is supposed to have.

Zener Diode

Although a linear regulator is a simple system for regulating voltage, what is even simpler is a Zener diode. The big difference is that a linear regulator like the IC LM78XX contains more than one component. Even though it is not that complex in its design, the Zener diode is even less complex because it doesn’t contain any other components. The Zener diode only uses one component to regulate voltage.

When voltage from a power source is sent to the Zener diode, any excess voltage beyond the voltage threshold is prevented from going to the electronic device. However, there is only a limited amount of power in which the Zener diode can handle. In fact, it can’t even handle as much power as the linear regulator, which is already a low-power voltage regulator. If you were to utilize a Zener diode as the sole regulator, then it would need to be in an extremely low power electronic device.

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Conclusion

Sometimes you’ll have linear regulators which use Zener diodes as one of their components. Other times, you’ll have a Zener diode by itself as the primary voltage regulator. If the electronic device is a very low power device, then you might find an advantage in using the Zener diode over the LM78XX because it won’t have a voltage drop. Only a trained electrician or electronics expert can make this determination.

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