Troubled to choose a voltage regulator between buck converter and 7805 voltage regulator

Posted by Component 7 19/06/2018 0 Comment(s)

Troubled to choose a voltage regulator between buck converter and 7805 voltage regulator

Why you choose buck converter instead of 7805 voltage regulator.

You are troubled to choose a voltage regulator between 7805 voltage regulator or the buck converter; because both converters convert the voltage from high to low and have various advantages and disadvantages. So first we see all the characteristics of both converters.

7805 regulator:

7805 regulators is a three-terminal voltage regulator which provides a fixed linear output voltage of +5VDC while input voltage varies from 7 VDC to 25 VDC and can handle up to 1500mA.

7805 regulators testing:

We apply 7 Volt DC supply at 500 milliamp current, and it gives 5 Volt DC supply at 500 milliamp current, so the voltage drop is 2 volts hence power loss obtain 1 watt from power formula P=VI, after that, we increase the current at 7 VDC input supply from 500mA to 1000mA then the power loss become 2 Watt.

If we apply maximum input voltage 25 VDC and maximum input current is 1500mA  then the power loss is 30 Watt.

This power loss converts into heat so we required a heatsink for heat dissipating from the 7805 regulators; more input supply voltage and current (more input power) need a larger heatsink for the proper working of this regulator.

Buck converter:

It is a device which step-down voltage ranging from max (a little bit lower than applied voltage) to zero voltage and have efficiency 88%-92% mean minimum power loses. Power loses in the buck converter is divided into 3 main sections

            1-  Inductor loss (Pl)

            2-  Semiconductor/Mosfet loss (P fet)

            3- Other loses ( like PCB copper trace loss, driver loss)

                             Total power dissipated = Pl+Pfet+other loses

As we see that buck converter have low loss so you don't need to add an extra heatsink.

 

 

Now we compare the feature of both converters

Efficiency: 7805 regulators have 20% to 40%  efficiency and buck converters have efficiency is 88%-92%.

Power Loss: As we see above 7805 have the lower efficiency which gives more power loss and required a heatsink. On the other hand, buck converter power loses is very low and it does not require an additional heat sink.

Design: 7805 regulator is the only one part so its design is very simple and buck converter has many parts and its design is a little bit complex.

Noise: 7805 regulators have very less noise in respect to the buck converter.

Buck converter never be used in radio communication devices because of this device use inductor which interfere the signal.

Cost: 7805 regulators come with the very low price around ₹10-15 and buck converter is the least bit expensive around ₹ 80-120.

We see that buck converter is more efficient than 7805 regulators when input power (voltage and current) is high and variable; it gives a constant voltage and does not require any additional heatsink. At the lower input and constant power supply, 7805 regulator is sufficient.

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