Engineers Garage

  • Projects and Tutorials
    • Electronic Projects
      • 8051
      • Arduino
      • ARM
      • AVR
      • PIC
      • Raspberry pi
      • STM32
    • Tutorials
    • Circuit Design
    • Project Videos
    • Components
  • Articles
    • Tech Articles
    • Insight
    • Invention Stories
    • How to
    • What Is
  • News
    • Electronic Products News
    • DIY Reviews
    • Guest Post
  • Forums
    • EDABoard.com
    • Electro-Tech-Online
    • EG Forum Archive
  • Digi-Key Store
    • Cables, Wires
    • Connectors, Interconnect
    • Discrete
    • Electromechanical
    • Embedded Computers
    • Enclosures, Hardware, Office
    • Integrated Circuits (ICs)
    • Isolators
    • LED/Optoelectronics
    • Passive
    • Power, Circuit Protection
    • Programmers
    • RF, Wireless
    • Semiconductors
    • Sensors, Transducers
    • Test Products
    • Tools
  • EE Resources
    • DesignFast
    • LEAP Awards
    • Oscilloscope Product Finder
    • White Papers
    • Webinars
  • EE Learning Center
    • Design Guides
      • WiFi & the IOT Design Guide
      • Microcontrollers Design Guide
      • State of the Art Inductors Design Guide
  • Women in Engineering

Buck Regulator Based Phone Charger

By Ganesh Selvaraj

This tutorial shows you how to make a phone charger which uses any DC source (AAA/AA/SLA battery) as input and is efficient in terms of power utilization.

Components Required:

1.LM2576 Switching regulator IC (5V version and not the adjustable version)
2.Inductor 100uH
3.Electrolytic Capacitors 100uF/25V, 1000uF/25V
4.1N5822 Diode
5.Small PCB
6.USB female connectors
7.Wires

Linear voltage regulators vs. switching voltage regulators:

We’ve been holding onto 7805 regulator IC  for a very long time and hence a question may arise as to why we  aren’t using the same this time. Well,  earlier we didn’t care about the efficiency since it was either a low current application or ones which didn’t run completely on battery but  now it is different. This time our aim is to create a device which runs on battery and needs to be utilizing the battery’s energy efficiently.
7805 or for that matter any linear voltage regulators are simple to use but quite inefficient. This is because they dissipate the voltage difference in form of heat. The amount of power wasted is given as

P = (Vin-Vout) X Iload

So for example if the input to the regulator is given from a 12V lead acid battery and the output voltage/current drawn is 5V/1A then the current drawn from the battery will also be 1 Amp so the power wasted in form of heat will be:

P = (12-5) X 1 = 7 Watts

Wasting 7 watts and that too through battery is pretty bad. And hence we need to think of an alternative. Well people have already thought about the alternative and that’s how switching regulators were born.

Switching regulators unlike the linear regulators regulate the output voltage by switching the storage elements (like capacitor or inductor) in different electrical configurations.

This is how a typical This is how a typical buck (step-down) regulator circuit looks like: looks like:

Typical Circuit Diagram of Buck Regulator

Fig. 1: Typical Circuit Diagram of Buck Regulator

Remember: Inductors do not like changing currents. They always try to oppose the change by creating a voltage drop across them.
When the switch is opened, no current passes through any components.
When the switch is closed, immediately, the current starts increasing in the circuit and the inductor opposes the change of current by developing a voltage drop. This voltage drop counteracts the voltage of source and hence the net voltage to the load decreases.
After a while, the rate of change of current decreases and eventually turns to zero (which means the current becomes constant) and hence the opposing voltage across the inductor also reduces. During this time the inductor stores the energy in form of magnetic field.

Image showing flow of current in Buck Regulator Circuit when switch is closed

Fig. 2: Image showing flow of current in Buck Regulator Circuit when switch is closed

When the switch is opened, the current again starts decreasing (i.e. changing) and hence again a voltage is developed in the inductor but this time, it adds to the source voltage instead of opposing it. The energy stored in the form of magnetic field is now utilized to supply the current to the load. If the switch is closed again before the inductor’s energy is completely used, then the voltage across the load always stays above zero.

Image showing flow of current in Buck Regulator Circuit when switch is open

Fig. 3: Image showing flow of current in Buck Regulator Circuit when switch is open

Here are the waveforms:

Image showing input and output waveforms of Buck Regulator Circuit

Fig. 4: Image showing input and output waveforms of Buck Regulator Circuit

Vi is the input voltage and VL is the voltage across the inductor.
Basically, the output voltage regulation is done by the Pulse Width Modulation technique. Remember hearing it somewhere? Yes, you did read about it in my project “DIY Table lamp” project. There  we used PWM to convert 12 Volts to 10 Volts for powering 3 LEDs in series without using a current limiting resistor. We also use the same principle to control the speed of DC motor.
But the only difference here is that we directly supplied the PWM signal to the LEDs in case of the lamp and here we would be smoothing out the signal (using the diode, inductor and capacitor) to get a fixed DC voltage.
So for example, if we want to step-down 15V to 5V then the regulator IC adjusts the Pulse Width (aka Duty Cycle) to 33%

Therefore, TON = 3 * TOFF

Setup

– Test the circuit on breadboard first and if everything works fine, then proceed to soldering.
– Once you are done with soldering, power the circuit using a 9V battery or couple of AA/AAA batteries or a SLA battery. Just     make sure that you provide more than 7 Volts in total.
– Test the USB’s output using a multi-meter set in voltmeter mode to see   if  +5V is coming or not. If it does, connect your            phone to it.
The regulator can handle 3 Amperes of current and hence we can charge more than one phone simultaneously if we are able to provide enough input power.

 

Circuit Diagrams

Circuit-Diagram-LM2576-IC-Based-Buck-Regulator


Filed Under: Circuit Design
Tagged With: Mobile Phone Charger
 

Questions related to this article?
👉Ask and discuss on Electro-Tech-Online.com and EDAboard.com forums.



Tell Us What You Think!! Cancel reply

You must be logged in to post a comment.

HAVE A QUESTION?

Have a technical question about an article or other engineering questions? Check out our engineering forums EDABoard.com and Electro-Tech-Online.com where you can get those questions asked and answered by your peers!


Featured Tutorials

  • Introduction to Brain Waves & its Types (Part 1/13)
  • Understanding NeuroSky EEG Chip in Detail (Part 2/13)
  • Performing Experiments with Brainwaves (Part 3/13)
  • Amplification of EEG Signal and Interfacing with Arduino (Part 4/13)
  • Controlling Led brightness using Meditation and attention level (Part 5/13)
  • Control Motor’s Speed using Meditation and Attention Level of Brain (Part 6/13)

Stay Up To Date

Newsletter Signup

Sign up and receive our weekly newsletter for latest Tech articles, Electronics Projects, Tutorial series and other insightful tech content.

EE Training Center Classrooms

EE Classrooms

Recent Articles

  • What are the battery-selection criteria for low-power design?
  • Key factors to optimize power consumption in an embedded device
  • EdgeLock A5000 Secure Authenticator
  • How to interface a DS18B20 temperature sensor with MicroPython’s Onewire driver
  • Introduction to Brain Waves & its Types (Part 1/13)

Most Popular

5G 555 timer circuit 8051 ai Arduino atmega16 automotive avr bluetooth dc motor display Electronic Part Electronic Parts Fujitsu ic infineontechnologies integratedcircuit Intel IoT ir lcd led maximintegratedproducts microchip microchiptechnology Microchip Technology microcontroller microcontrollers mosfet motor powermanagement Raspberry Pi remote renesaselectronics renesaselectronicscorporation Research samsung semiconductor sensor software STMicroelectronics switch Technology vishayintertechnology wireless

RSS EDABOARD.com Discussions

  • Timer MC14541B wrong delay
  • Pull up via GPIO
  • Electrical Lenght of Microstrip Transmission Lines
  • How to Draw/Display a BMP or PNG on 3.2" TFT Display with inbuilt ILI9341 IC
  • file edit

RSS Electro-Tech-Online.com Discussions

  • DIY bluetooth speaker
  • Turn CD4029 on/off with TTP223
  • Need a ducted soldering fan for solder smoke extraction
  • Question about ultrasonic mist maker
  • Power failure relay options
Engineers Garage
  • Analog IC TIps
  • Connector Tips
  • DesignFast
  • EDABoard Forums
  • EE World Online
  • Electro-Tech-Online Forums
  • Microcontroller Tips
  • Power Electronic Tips
  • Sensor Tips
  • Test and Measurement Tips
  • 5G Technology World
  • About Us
  • Contact Us
  • Advertise

Copyright © 2022 WTWH Media LLC. All Rights Reserved. The material on this site may not be reproduced, distributed, transmitted, cached or otherwise used, except with the prior written permission of WTWH Media
Privacy Policy | Advertising | About Us

Search Engineers Garage

  • Projects and Tutorials
    • Electronic Projects
      • 8051
      • Arduino
      • ARM
      • AVR
      • PIC
      • Raspberry pi
      • STM32
    • Tutorials
    • Circuit Design
    • Project Videos
    • Components
  • Articles
    • Tech Articles
    • Insight
    • Invention Stories
    • How to
    • What Is
  • News
    • Electronic Products News
    • DIY Reviews
    • Guest Post
  • Forums
    • EDABoard.com
    • Electro-Tech-Online
    • EG Forum Archive
  • Digi-Key Store
    • Cables, Wires
    • Connectors, Interconnect
    • Discrete
    • Electromechanical
    • Embedded Computers
    • Enclosures, Hardware, Office
    • Integrated Circuits (ICs)
    • Isolators
    • LED/Optoelectronics
    • Passive
    • Power, Circuit Protection
    • Programmers
    • RF, Wireless
    • Semiconductors
    • Sensors, Transducers
    • Test Products
    • Tools
  • EE Resources
    • DesignFast
    • LEAP Awards
    • Oscilloscope Product Finder
    • White Papers
    • Webinars
  • EE Learning Center
    • Design Guides
      • WiFi & the IOT Design Guide
      • Microcontrollers Design Guide
      • State of the Art Inductors Design Guide
  • Women in Engineering