【Electronic Construction Basics】Two Power Supply Methods to Learn from Power Supply Pins on Microcontroller Boards|Introduction to Practical Electronics Circuits Starting with LTspice


Table of Contents
0:00 Opening
0:22 What is a power pin?
1:20 Characteristics of the two types of power supplies
3:14 Demonstration of actual equipment
4:13 One Point Advice
4:38 Summary.

Two Power Supply Methods Learned from Microcontroller Board Power Supply Pins|Introduction to Practical Electronic Circuits with LTspice

I'm not familiar with the features of the power supply system, I wish I knew more about it.

Then I'll explain the subject of the contents of the power supply pins on the microcontroller board!

For those who want to learn more about power supply methods, we will talk about " two power supply methods learned from microcontroller board power supply pins ".

This article will give you a better understanding of the characteristics of linear and switching systems, so please read it all the way through.

What is a power pin?

Let us begin with a brief description of the power supply pins.

What we call power pins here are the pins in the I/O pins of the microcontroller board that supply power such as 5V or 3.3V.
For example, in Aruino, the area indicated by the zeros in the following image is the pin.


There are several types of microcontroller boards as shown below, but they all have the same basic configuration.

microcontroller board

First, 5V is supplied to the microcontroller board via USB and output directly from the 5V pin.
For the 3.3V pin, 3.3V made from 5V is output via a voltage converter.

What is a power pin?

The voltage conversion part here is technically called a DCDC converter.

DCDC means "to convert from one DC voltage to another DC voltage.

What is DCDC?

Two power supply methods

In fact, there are two types of DCDC converter methods: linear and switching, each with different characteristics.

DCDC converter method

Please keep in mind here that understanding the features will help you use the system more safely!

Let us introduce the two power supply methods.

linear system

The first power supply method is the "linear method.

What is the Linear Method?
A method of connecting a variable resistor in series with a load and outputting the desired voltage by adjusting the size of the resistor. (*Refer to the image below)

What is the Linear Method?

The operation and use of the above regulator is very simple, and it is also called a "three-terminal regulator" because it has only three component terminals.

It also has the advantage of a very fast time loop to adjust for voltage fluctuations, making it easier to stabilize the voltage.

Advantage of voltage stability

On the other hand, there are also linear regulators, which regulate voltage by converting power into heat and releasing energy, as shown in the figure below.

Linear regulator

This has the disadvantage that it tends to generate heat and cannot carry a large current.

Disadvantage of easy heat generation and large current flow

The linear method can be summarized as follows

Advantages of the Linear Method
  • Simple operation and easy to use
  • Small voltage fluctuations
Disadvantages of the linear method
  • High power consumption

switching regime

The second power supply method is the "switching method.

What is a switching system?
A method of adjusting voltage using a switch. (See image below)

What is a switching system?

The operation is somewhat more complicated than the linear method, but simply put, the voltage is regulated by storing energy in a capacitor when the switch is on and releasing it when the switch is off.

The magnitude of the output voltage can be changed by this on/off time ratio.

Output voltage magnitude

Unlike the linear method, the switching method has the advantage of low power consumption because it converts voltage by changing the form of energy rather than consuming energy.

On the other hand, the disadvantages are that a large number of components are required and that voltage fluctuations are large.

Disadvantages of the switching method

The switching method can be summarized as follows

Advantages of the switching method
  • Low power consumption
Disadvantages of the switching method
  • Large number of parts
  • Large voltage fluctuations

Now that we know the difference between linear and switching methods, let's look at which microcontroller boards in the world use which!

The following image shows a table summarizing how the 3.3V outputs of recently popular microcontroller boards are made.

Differences between microcontroller boards

As a conclusion, it seems that the linear method is used for boards with limited applications or those that emphasize miniaturization , while the switching method is used for boards that appeal to a wide range of applications and functions.

Thus, both methods are prevalent in the world and are used by the right people at the right time.

The biggest difference between these two methods is their power consumption.

The biggest difference between the two methods is the power consumption

So, finally, let's connect the loads and see how much the heat actually differs between each method.

As a representative here, I used the 3.3V power pins of the microbit and M5Stack BASIC microcontroller boards.

3.3V power pins on microbit and M5Stack BASIC microcontroller boards

As for the load, the ultrasonic atomizing module commonly used in humidifiers was just right for the size of the load, so we connected this to monitor the temperature.

Ultrasonic atomizing module commonly used in humidifiers

The load of the ultrasonic atomizing module is about 5 to 10 ohms in terms of resistance value. approximately 5 to 10 ohms resistance equivalent.

When I first connected the microbit with the linear method, the temperature became much higher as shown here.

linear system

On the other hand, with the M5Stack, which is a switching system, we were still able to confirm that temperatures were considerably suppressed.

switching regime

So, on the subject of microcontroller board power supply pins, we introduced two power supply methods and their characteristics.

The actual difference in power values is explained in the CQ Publishing newsletter, so please refer to that for the rest of the article.

advice of a point (advice that may be helpful to some people)

In addition, I would like to offer one final piece of advice.

Although the microcontroller board is connected for demonstration purposes, it is basically not designed to supply a large current, so it is safer not to connect a large load such as a motor or ultrasonic spraying module.

When you want to use these components, be sure to use a power supply that can handle high current, such as a power adapter or nickel-cadmium battery!


In this issue, we dissected the contents of the power supply pins on a microcontroller board.
Using LTspice, you can easily simulate operation and power consumption, so if you are "afraid of moving things around," please make use of that as well.

We also post other videos and articles that help beginners learn electronics from scratch in a systematic way, including explanations of the minimum knowledge and tools that a beginner in electronics should acquire.

If you are just getting started with electronics, be sure to check out our other articles and videos!