Hello, electronics enthusiasts!

Today we’re going to dive into the fascinating world of SMPS (Switched-Mode Power Supply) with a practical and powerful project: a 13.8V power supply capable of delivering up to 10A of continuous current! This project uses the efficient PWM controller IR2153 and the robust MOSFET transistors IRF840, components that together form an unbeatable combination in terms of cost-effectiveness and performance.

Whether you’re a student, a professional in the field, a designer, or a hobbyist looking for a reliable power supply for your applications, this article is for you! We’ll unravel each step of this circuit together, from theory to practice, with clear and detailed explanations.

🔍 What is a Switched-Mode Power Supply (SMPS)?

Before diving into the project, let’s understand what makes switched-mode power supplies so special. Unlike traditional linear power supplies, which dissipate excess energy as heat, SMPS operate with high-frequency switching, resulting in higher energy efficiency and reduced size.

Think of an SMPS as an intelligent system that rapidly “turns on and off” the power, adjusting it to provide exactly what your circuit needs. This switching process occurs at very high frequencies (typically above 20kHz), allowing the use of smaller and lighter components.

🔧 Detailed Circuit Analysis

Our 13.8V 10A SMPS power supply project can be divided into 8 fundamental stages, each playing a crucial role in the overall functioning of the circuit. Let’s explore each of them:

1️⃣ Protection Circuit

Safety comes first! Our protection circuit consists of a 5A/250V Fuse, which acts as a bodyguard, interrupting the circuit in case of a dangerous overcurrent. In parallel, we have an NTC (Negative Temperature Coefficient), a special thermistor that limits the initial surge current.

Think of the NTC as an “intelligent traffic light” for electricity: when the circuit is turned on, it offers high resistance, limiting the initial current. As it heats up, its resistance decreases, allowing normal current flow to occur. This topology is found in most modern SMPS, such as those in laptops and computers.

2️⃣ Transient Filter

This stage acts as a “traffic guard” for electricity, preventing high-frequency noise from traveling between our circuit and the power grid. It consists of an initial capacitive filter (C1, C2) that inhibits high frequencies from returning to the grid, and an EMI (Electromagnetic Interference) filter choke, which attenuates the noise generated by switching.

3️⃣ Primary Rectification

Here, the alternating current from the power grid (110V or 220V) is converted into pulsating direct current through the rectifier bridge D1. It’s as if we’re transforming the bidirectional flow of electricity into a unidirectional flow, preparing it for the next stages.

4️⃣ Primary Filter

The capacitors C3 and C4 act as energy reservoirs, smoothing the ripple of the pulsating direct current and providing a more stable voltage for the switching stage. Think of them as small “energy lakes” that ensure a constant flow.

5️⃣ Switching Stage

This is the “magic” of the switched-mode power supply! The heart of this stage is the IR2153 IC, a PWM (Pulse Width Modulation) controller that generates high-frequency signals to control the MOSFET transistors Q1 and Q2 (IRF840). These transistors function as ultra-fast switches, turning on and off at high frequency to “slice” the direct voltage into high-frequency pulses.

The IR2153 is particularly interesting because it already incorporates a driver for MOSFETs in its 8-pin package, significantly simplifying the design and reducing the component count.

6️⃣ High-Frequency Transformer

Unlike conventional transformers that operate at 60Hz, our Chopper Transformer operates at high frequency, allowing a drastically reduced size with the same power capacity. It is responsible for two crucial functions: galvanically isolating the output circuit from the power grid (essential for safety!) and transforming the high voltage of the primary to the low voltage needed in the secondary.

7️⃣ Fast Rectification

In the secondary of the transformer, we need to convert the high-frequency pulses back into direct current. For this, we use the fast diode D3 (MBR3045PT), which is capable of operating efficiently at the high frequencies generated by our circuit. Common diodes would not be suitable here due to their slow recovery time.

8️⃣ Output Filter

Finally, the inductor L2 and the capacitor C9 form an LC filter that smooths the residual ripple, providing a clean and stable output voltage of 13.8V. It’s the last barrier between the rectified pulses and the perfectly usable energy that will power your projects.

⚡ The IR2153 PWM Controller in Detail

The IR2153 is the brain of our switched-mode power supply. This integrated circuit from International Rectifier (now part of Infineon) is specifically designed for half-bridge applications in switched-mode power supplies, combining an oscillator with MOSFET drivers in a single package.

The IC is powered through the power resistor R3 (27K 5W) together with the capacitor C5. Internally, the IR2153 already has a 15.6V Zener diode to regulate its power supply, but the available current is limited. Therefore, it’s crucial not to use a resistor R3 with a value lower than specified, as this could overload and damage the IC.

An interesting improvement would be to add an external 15V Zener diode in parallel with the IC’s power supply, providing additional protection and greater stability.

It’s worth highlighting an important difference between the IR2153 and the IR2153D: the “D” model already incorporates internally the diode D2 (FR107 or BA159) necessary for the proper functioning of the circuit. If you’re using the IR2153D, you can omit this component. If it’s the IR2153 (without the “D”), keep the diode D2 as shown in the schematic.

🔌 Complete Schematic Diagram

Now that we understand each part of the circuit, let’s examine the complete schematic diagram in Figure 2. This is the moment when all the pieces of the puzzle fit together, forming a cohesive and functional system.

🔧 The Transformer: Heart of the Switched-Mode Power Supply

The transformer TR1 is a critical component in our power supply. For this project, we used a transformer model IE-35A recovered from a scrap ATX power supply. The good news is that practically any ATX power supply transformer can be used, as long as we follow the correct pinout.

One of the great advantages of this project is that there is no need to rewind the transformer! You just need to correctly identify the terminals and connect them as shown in Figure 3 below. This approach saves time and eliminates one of the most complex steps in building switched-mode power supplies.

In addition to the EI-35A model, other transformers from AT or ATX power supplies can be used, such as the models EI-33, ER35, TM3341101QC, ERL35, EI28, among others. Figure 4 shows an example of the EI-35A transformer we used:

As for the inductors L1 and L2, both can be salvaged from the original ATX power supply. The inductor L1 is the input EMI filter, while L2 is the output filter. If you prefer to build your own filter, you can wind an inductor on a ferrite toroidal core using 0.6 mm enameled copper wire with approximately 25 turns.

📝 Complete List of Components

To facilitate your assembly, we’ve compiled a detailed list of all the necessary components for this project:

🖨️ Printed Circuit Board (PCB)

To facilitate your assembly, we’ve made the PCB (Printed Circuit Board) files available in different formats, covering all your needs, whether for a homemade assembly or for sending to a professional fabrication.

The files are available in GERBER format (for professional fabrication), PDF (for viewing and printing) and PNG (for visual reference). And best of all: they are available for free download directly from the MEGA server, through a direct link, without any complications or redirections!

📥 Download Files

To download the necessary files for assembling the electronic circuit, just click on the direct link provided below:

Link to Download: Download Files (PCB Layout, PDF, GERBER, JPG)

🎓 Conclusion and Next Steps

Building your own SMPS power supply is a challenging but extremely rewarding project. Besides saving money, you gain deep knowledge about how modern power supplies work, essential in practically all electronic equipment we use daily.

We hope this detailed guide has been useful for your journey in electronics. Always remember to prioritize safety when working with circuits connected to the power grid and don’t hesitate to seek help if you have doubts.