Buck Converter vs Linear Voltage Regulator

Linear voltage regulators are best for simplicity and clean power, while buck converters are best for efficiency and power-hungry systems.

In this video author is comparing in practice a buck converter with the LM7805 linear voltage regulator. Here is the showdown between the dc-dc converter vs linear voltage regulator.

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If you want to step down a higher DC voltage to a lower one, you have two main choices:

• Linear Voltage Regulator: Simple, cheap, quiet, easy to use, but not very efficient and wastes a lot of power as heat.

• Buck Converter: More complex and slightly noisier, but very efficient (often 90%+), wastes less energy, and is better for high power or battery applications.

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In simple terms:

Use a linear regulator when:

• Your power difference (Vin minus Vout) is small
• Noise and ripple must be extremely low
• Simplicity and cost matter more than efficiency

Use a buck converter when:

• Efficiency and low heat are important
• You need high current or big voltage drops
• You are powering battery-powered or high-power devices

Let’s go deeper.

What Is a Linear Voltage Regulator?

A linear voltage regulator is the simplest way to get a steady lower voltage from a higher supply voltage. It works by acting like a controllable resistor that drops the extra voltage and keeps the output steady.

Because it works like a controlled resistor, the excess energy is burned off as heat. That means if you step down from 12 V to 5 V at 1 A, the extra 7 V at 1 A is wasted as heat.

Pros of Linear Regulators

Cons of Linear Regulators

• Very low efficiency when the voltage drop is large

• Generates a lot of heat

• Not ideal for battery-powered or high-current systems

• Only step-down (buck) operation — cannot step-up or buck-boost

What Is a Buck Converter?

A buck converter is a type of switch-mode power supply (SMPS) that uses a high-frequency switching transistor, an inductor, and a capacitor to efficiently step down DC voltage. Instead of burning excess voltage as heat, it “chops” the voltage and uses energy storage to deliver efficient power.

What makes a buck converter powerful is that it converts energy rather than dissipates it, so it can reach very high efficiency (often above 90 percent).

Pros of Buck Converters

• High efficiency (less heat, longer battery life)

• Suitable for high current loads

• Can handle large differences between input and output voltages

• Saves energy and reduces voltage loss

Cons of Buck Converters

• More complex design and layout

• Requires more components (inductor, switching elements, capacitors)

• Produces switching noise and ripple (can be filtered but still higher than linear)

Key Difference: Efficiency and Heat

Efficiency is the main distinction between the two:

• Linear regulator efficiency is roughly (Vout / Vin). If you drop from 12 V to 5 V, the maximum theoretical efficiency is about 41 percent, and most of the rest is heat.

• Buck converters use stored energy in inductors and switching transistors, and they can often achieve 80 percent to over 90 percent efficiency in real circuits.

In actual terms, a linear regulator might get hot under load, while a buck converter stays cooler and wastes much less power.

Noise and Ripple: Which One Is Cleaner?

Another big difference is output quality:

• Linear regulators produce very clean, low-noise output with minimal voltage ripple and EMI (electromagnetic interference). This makes them great for audio circuits, RF modules, and precision analog systems.

• Buck converters switch at high frequency. That means they generate ripple and switching noise, which can affect sensitive circuitry if not properly filtered.

So if signal purity is critical and you do not care much about efficiency, a linear regulator can be a better choice.

Size, Complexity, and Cost

• Linear regulators are small, cheap, and require few external components. A typical LDO (low-dropout regulator) needs just a couple of capacitors.

• Buck converters require an inductor, a switching transistor, diodes or synchronous MOSFETs, and filtering components. This makes them larger and more complex, and sometimes slightly more expensive at low volumes.

However, the overall system cost of a buck converter can be lower than a linear regulator when you factor in the need to manage heat with heat sinks and cooling in high current applications.

Typical Use Cases

Here are real world examples of where each is best:

Best Uses for Linear Regulators

• Low power circuits where efficiency is not critical

• Noise sensitive analog and RF systems

• Simple designs and small PCB spaces

• Reference voltages and sensor modules where ripple matters

Best Uses for Buck Converters

• Battery powered devices where efficiency extends life

• High current loads like motor controllers, LED drivers

• Systems with large input to output voltage differences

• Power supplies for microcontrollers and SBCs where heat is a concern

Simple Comparison Table

Final Recommendation

• Choose a buck converter when you need efficiency, high current, and low heat.

• Choose a linear regulator when you want simplicity, low noise, and low cost for smaller loads.

In most modern power supply designs, buck converters are preferred because they waste far less energy and reduce thermal stress. However, linear regulators still hold an important place in noise-sensitive designs and simple circuits.

In the video:

• Why & when you should use Buck converters?
• Advantages of linear voltage regulators
• Disadvantages of linear voltage regulators
• How to use linear voltage regulator?
• Where is buck converter used?
• Availability of Buck converters.
• Nomenclature with voltage regulators,
• How to use buck converters?
• Comparison of their usage,
• Testing both under loads for long time,
• Drawbacks of buck converters

What you learn from the comparison:

• Linear voltage regulator (78xx) use a lot more voltage compared to buck converter.
• Linear voltage converter heats up a lot to dissipate extra current,
• It switches off after heating up, and switches back on again.
• It consumes a lot more power compared to buck converter,
• Buck converter can provide variable output (by varying the potentiometer), whereas, a linear voltage regulator is stuck at only 1 output.

There are 2 mistakes in the video:

1. 5:02 – 5:08 – correct calculations should be: (12V – 5V) x 0.42A = 2.94W
2. 5:17 – 5:23 – correct calculations should be: (12V – 5V) x 0.22A = 1.54W

Courtesy: ElectronFun.com