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5V, 12V Buck Converter Circuit SMPS 220V

Last Updated on January 15, 2025 by Admin Leave a Comment

Featuring 90% efficiency, this step-down buck converter can transform a 220V AC input from the mains supply into 5V, 12V, or 24V DC.

The indicated buck converter is an SMPS circuit that makes use of STMicroelectronics' IC VIPer12A.

VIPer12A compressed

The circuit we designed uses very few external components. It operates directly from mains AC input.

Buck Converter Design

In the circuit diagram, we see the input stage. It includes a surge-limiting resistor that acts like a fuse. There is also a diode for rectifying AC and an LC filter network to reduce DC ripple.

LC Filter Functionality

The LC filter stabilizes the DC output. It also improves electromagnetic interference (EMI) response. We can add capacitor Cin1 to enhance EMI performance.

Main PWM Processor

The IC VIPer12A is our main PWM processor. It handles the entire buck conversion process.

Main Features

Here are the main specifications of our configuration:

  1. AC Input Voltage (Vinac): 80 - 285 Vac
  2. Output Current (Iout): 30 mA
  3. Output Current (Iout): 250 mA
  4. Output Voltage (Vout1): +24 ± 10% V
  5. Output Voltage (Vout2): +5 V ± 5%
  6. Switching Frequency: 60 kHz
  7. Output Power: ~1 W

How It Works

Our circuit provides two outputs. The 24V output comes from a buck converter. The 5V output uses flyback mode.

We get feedback voltage for regulation from Vout1. This voltage also connects to the IC's Vdd pin.

This setup simplifies wiring. We only need one high-voltage diode and one capacitor (D1 and C3). This makes connections easier and cheaper.

The inductor L has two windings on a common ferrite core.

The windings have specific turn ratios: N1 = 200 turns and N2 = 60 turns. Both are wound on a PANASONIC ELC10D152E ferrite core.

elc10d101e 1

We installed Zener diodes Z1 and Z2 to protect the outputs from overvoltages.

We fixed a dummy load resistor across Vout1 to ensure proper regulation during open load situations.

While this resistor slightly affects efficiency, it significantly enhances the voltage regulation response of the circuit.

We used fast response, fast recovery rectifier diodes at the output. D1 is a high voltage diode to handle the high reverse voltages from the DC bus. D2 is a standard diode.

5V, 12V Buck Converter Circuit SMPS 220V

Parts List for the proposed simple SMPS buck converter circuit:

ComponentSpecification
Rr10Ω, 1/2W
Rf10kΩ, 1/4W
R(load)4.7kΩ, 1/4W
Cin4.7 μF, 450V Electrolytic Capacitor
C133 μF, 50V Electrolytic Capacitor
C2100 μF, 16V Electrolytic Capacitor
C31 μF, 25V Electrolytic Capacitor
C422 nF Ceramic Capacitor
DrDiode 1N4007
D1Diode BA159 (fast)
D2Diode 1N4148 (fast)
D3Diode 1N4004
Dz22V Zener
Dz127V Zener
Dz25.6V Zener
L10.5 mH
Lf470 μH Inductor
IC1STMicroelectronics VIPer12ADIP

The PCB design and components arrangement of the IC VIPer12A-based SMPS buck converter circuit described above

5V, 12V Buck Converter PCB design

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Tagged With: 12V, 220V, Buck, Converter, SMPS

About Admin

Hey friends, Thanks a bunch for stopping by this site! I am an engineer with a Bachelor of Engineering in Electronics and Telecommunication. One of my passions is gathering information from all sorts of electronics books and tutorials. I then take that information and compile it into a language that is super easy to understand. My goal is to make those complex electronics circuit concepts and technical terms much more accessible for all the new and budding electronics engineers out there. I can also design customized circuit diagrams as required by the users.
If you have any questions related to this field, please do not hesitate to drop a comment! I am always here and ready to help you out with any queries you might have. I cannot wait to hear from you!

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