How To Build XL4015 DC DC Buck Converter Module - Circuit Digest

In this article, we will be learning about the features and working of the XL4015, which is a 5A 180KHz 36V Buck DC to DC Converter. Here we will desolder all the components from the module, completely reverse engineer the schematic and make the PCB from it, so that we can order the components and make the PCB ourselves. The XL4015 DC-DC buck converter is a versatile step-down converter that provides both constant current (CC) and constant voltage (CV) regulation. In addition, we'll test the module and compare all the datasheet parameters to see if they hold true or not. So without further ado, let's get right into it. This complete guide will provide you with the DC to DC buck converter circuit diagram outlines, reverse engineering, PCB layout, and practical testing to enable you to understand the dc dc buck converter working principle and build your own module.

XL4015 DC-DC Buck Converter Module - Quick Overview

Build Time: 6-8 hours | Cost: $10-20 | Difficulty: Intermediate

What You'll Learn: PWM switching, Constant Current/Voltage regulation, PCB design, Circuit debugging

Applications: Battery charging, Voltage regulation, LED driving, Power supply prototyping

Table of Contents

• Working Principle

• Module Features

• Specifications

• Components Used

• Circuit Diagram Analysis

• Testing the Module

• Problems Encountered while Testing

Understanding DC-DC Buck Converter Working Principle

The core concept behind a dc dc buck converter working principle is the combination of energy storage in an inductor and switching controls. The XL4015 IC contains an internal MOSFET switch and controls the output voltage using PWM (Pulse Width Modulation) to make the MOSFET switch's duty cycle larger or smaller. When the switch is closed, the inductor will draw a current and store energy. In other terms, during this type of operation, the work done on the inductor is transferred to the output via the freewheeling diode. This switching of the inductor and switch allows continuous energy delivery to the load without any breaks in current.

Some key components are defined during the buck converter operation:

• Switching Element: Internal MOSFET implemented on XL4015
• Energy storage: Inductor (Usually a 68µH Inductor)
• Freewheeling Diode: SS54 Schottky Diode for good efficiency
• Filter Capacitors: Input and Output Smoothing

XL4015 DC to DC Buck Converter Module Features

This DC to DC buck converter module combines a Constant Current (CC) and Constant Voltage (CV) converter, which comes in very handy in various conditions. For example, if you want to charge a lithium battery with a constant current, you can do that very easily with this module. Furthermore, if you are testing a circuit and powering it for the first time, it's always recommended to use a constant current that will limit damage to your circuit if you made any mistakes in the build process.

XL4015 Buck Converter Specifications

In the above image, you can see first we have the DC input connector, which is to connect to an unregulated power source. Next, we have two 10K potentiometers that are used to set the constant current and voltage level. Furthermore, there are three LED indicators on the board; the first one near the input connector shows when the module is in constant current mode, while the other two near the output are mainly for battery charging applications (battery charging and battery full indicators). Other than that, this IC has an input voltage range of 8V to 36V, and the output voltage of the device is 1.25V to 32V. With max load, the PWM of the device can reach 100% duty cycle, and it can operate on a 180 kHz operating frequency. The constant output current of the module is 5A, and it can reach up to 96% efficiency while working. Regarding protection features, the device includes thermal shutdown, short-circuit protection, and current limit functionality.

Components Used in the DC-DC Buck Converter

Before we look at the schematic, here is a list of components that are required to build the XL4015 Buck Converter Circuit. Building your own DC to DC buck converter module requires specific components. The main component in this board is the XL4015 buck converter IC, which is a 5-pin IC designed and developed by XLSEMI which is a well-known manufacturer in China and very famous for producing compact buck and boost converter ICs. The list of components required to build the 5A Buck Converter Circuit is shown below-

• XL4015 Buck Converter IC - 1
• 78L05 Voltage Regulator - 1
• LM358 op-amp - 1
• SS54 Schottky Diode- 1
• TL431 Programmable Reference - 1
• 470uF,35V Capacitor - 2
• 10uF 0805 Capacitor -2
• 10K Ten Turns Trim Pot - 2
• 0.1uF Capacitor - 3
• 270R Resistor - 1
• 1K Resistor - 2
• 2.2K Resistor - 1
• 10K Resistor - 1
• 71.5K Resistor - 1
• 90.9K Resistor - 1
• LED 0805 - 3
• Screw Terminal - 2