Self Switching Mode Power Supply with Optocoupler and TL431 Voltage Regulation 12V 5A

12V Switching Power Supply Circuit Diagram

Self Switching Mode Power Supply with Optocoupler and TL431 Voltage Regulation 12V 5A electrobuff.blogspot.com

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How a Switching Mode Power Supply Works

A switching mode power supply (SMPS) is an electronic circuit that efficiently converts electrical power from one form to another, typically from mains AC voltage to a regulated DC output. Let's break down the key components and processes involved in a typical SMPS:

Input Filter:

The SMPS begins with an input filter that reduces electromagnetic interference (EMI) and radio frequency interference (RFI) from the incoming AC power. This filter typically includes inductors and capacitors.

Rectification and Smoothing:

The filtered AC power is then rectified to convert it into pulsating DC using a diode bridge. This pulsating DC is then smoothed using a capacitor to reduce voltage fluctuations.

Power Factor Correction (PFC):

In order to improve the power factor and make the power supply more efficient, a power factor correction stage is often employed. This corrects the phase relationship between the input voltage and current, minimizing wasted power.

Switching Transistor:

The heart of the SMPS is the switching transistor, which rapidly switches the DC voltage on and off. This process enables high-frequency AC voltage to be generated, reducing the size of the transformer and improving efficiency.

Controller IC:

A controller IC (Integrated Circuit) is responsible for regulating the output voltage. It monitors the output voltage and adjusts the switching frequency of the transistor to maintain a stable output.

Ferrite Power Transformer:

The high-frequency AC voltage generated by the switching transistor is then passed through a ferrite power transformer. The transformer steps down or steps up the voltage as required, and its compact design is made possible by the high frequency of operation.

Output Rectification and Smoothing:

The transformer output is rectified again using diodes to convert the AC voltage back to DC. Another smoothing capacitor further reduces voltage ripples, resulting in a relatively stable DC voltage.

Voltage Feedback and Regulation using Voltage Reference IC:

A portion of the output voltage is fed back to the controller IC through a voltage feedback loop. The controller compares this feedback voltage with a reference voltage from a precision voltage reference IC. Any deviations trigger adjustments in the switching frequency to maintain the desired output voltage.

Optocoupler:

An optocoupler is often employed to provide electrical isolation between the input and output sides of the SMPS. It uses a combination of an LED and a photodetector to transmit the feedback signal while maintaining isolation.

This combination of components and processes allows the switching mode power supply to efficiently regulate the output voltage while minimizing size and maximizing energy efficiency