UC3843 Switching Mode Power Supply (SMPS) Circuit 12V, 10A 120Watts!
UC3843 Switching Mode Power Supply (SMPS) Circuit 12V, 10A 120Watts!
UC3843 Switching Mode Power Supply Complete Circuit Diagram
UC3843 Switching Mode Power Supply (SMPS) Circuit electrobuff.blogspot.com
UC3843 SMPS Overview
Hi. In today's tutorial I'll show you how to make a switch mode power supply based on the UC3843 PWM driver IC. The feasible power output is approximately 120W (12V, 10A). The project requires only a handful of components and the circuit is of moderate complexity. It follows a Flyback SMPS topology, the output voltage can be easily modified for any value from 5-30V by simply altering the secondary windings.
Watch my YouTube Video Tutorial:
How the Power Supply Circuit Works:
The circuit is a classic Flyback DC DC converter. Here's a little overview of a Flyback converter.
How a DC to DC Flyback Converter Works:
A DC-DC flyback converter is a type of switched-mode power supply (SMPS) that is widely used to convert a DC input voltage to a different DC output voltage. It operates on the principle of energy storage and transfer and is characterized by its ability to provide galvanic isolation between the input and output.
Key features and principles of a DC-DC flyback converter:
Topology:
The flyback converter belongs to the class of transformers-based converters. It uses a transformer to store energy during the first half of the switching cycle and then releases that energy to the output during the second half of the cycle.
Transformer Operation:
The transformer in a flyback converter stores energy in its magnetic field when the input voltage is applied, and then transfers that energy to the output during the off state of the switching transistor.
The transformer provides galvanic isolation between the input and output, making the flyback converter suitable for applications requiring isolation.
Switching Operation:
The heart of the flyback converter is a switching transistor that controls the energy flow through the transformer.
During the on state of the transistor, energy is stored in the transformer's primary winding.
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| Flyback DC DC Converter basic circuit electrobuff.blogspot.com |
When the transistor turns off, the energy is transferred to the secondary winding and subsequently to the output.
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| Flyback DC DC Converter Circuit Operation Principle electrobuff.blogspot.com |
Energy Storage Element:
A flyback converter typically includes a capacitor connected to the transformer's secondary winding. This capacitor stores energy during the off state of the transistor and helps regulate the output voltage.
Voltage Regulation:
The output voltage of a flyback converter can be regulated by controlling the duty cycle of the switching transistor. This is achieved through feedback control mechanisms that monitor the output voltage and adjust the duty cycle accordingly.
Applications:
- Flyback converters are commonly used in various applications, such as power adapters, battery chargers, LED drivers, and other low to medium power electronic devices.
- Their ability to provide galvanic isolation makes them suitable for applications where isolation between input and output is crucial.
Advantages:
- Galvanic isolation between input and output.
- Simple topology with fewer components.
- Versatility in input and output voltage configurations.
Disadvantages:
- Limited to lower power applications compared to some other converter topologies.
- Transformer design can be complex, especially when dealing with high-frequency operation.
In summary, a DC-DC flyback converter is a versatile and widely used power supply topology, providing galvanic isolation and efficient energy transfer for various electronic applications. Its simplicity and suitability for low to medium power applications make it a popular choice in the design of power conversion circuits.
UC3843 Switching Mode Power Supply (SMPS) Circuit Operation Images
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| UC3843 Switching Mode Power Supply (SMPS) DC DC Flyback Circuit electrobuff.blogspot.com |
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| UC3843 Switching Mode Power Supply (SMPS) DC DC Flyback Circuit electrobuff.blogspot.com |
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| UC3843 Switching Mode Power Supply (SMPS) DC DC Flyback Circuit electrobuff.blogspot.com |
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| UC3843 Switching Mode Power Supply (SMPS) DC DC Flyback Circuit electrobuff.blogspot.com |
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How do we convert this to a variable Voltage and Current Power Supply?
ReplyDeleteTo convert the circuit to provide variable voltage, you will need to make modifications to the secondary side of the power supply to include a voltage sensing circuitry and a feedback mechanism. You can use TL431 precision voltage reference IC to sense secondary output voltage, and PC817 optocoupler to provide feedback to the UC3843 PWM IC.
DeleteTo get adjustable current, you can either modify current sensing on the primary side (Resistor R9) by incorporating a potentiometer in parallel with R9, or modify the secondary side of the power supply to include a shunt current sensing resistor in series with the load.
Thank you very much for your prompt reply. Could you please publish the modified circuit for guidance of your readers? Thanks again for your patience.
ReplyDeleteI wonder that's at the C8, how much volt of cap should I use?
ReplyDeleteAnd the others cap in the circut, how much volt that I should use for those caps?
I'm sorry because my english is not really good.
C8 is a polypropylene capacitor rated for 400V AC. all the other capacitors other than C1 are rated for at least 25V.
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