Simple 12V 5 Amp SMPS Circuit

The design and building of a 12V 5 Amp SMPS circuit with MOSFET and optocoupler feedback is explained thoroughly in this post.

It is around 85% accurate.

What is a 12V 5 Amp SMPS Circuit:

A 12V 5A SMPS Switched Mode Power Supply circuit is designed to provide a stable and regulated 12V DC output with a maximum current of 5 amperes.

SMPS circuits are commonly used in various electronic applications where efficient power conversion is required such as powering electronic devices, LED lighting systems or charging batteries.

Further we will explore the unique construction details and formulas that set this power supply apart.

Circuit Working:

Parts List:

The key role is the dynamic control of the flyback inverters through a MOSFET power switch.

During setup the MOSFET gate is charged using a 470k resistor which motives it to activate.

Fast and complete MOSFET opening happens through positive feedback methods.

Energy builds up in the core of the transformer when the primary connects to 325V.

Therefore a voltage drop occurs across the 0R22 current detecting resistor as the primary current rises.

The KC507 transistor opens when there is a 0.5V voltage drop across the current sensing resistor.

The MOSFET gate then drops as a result of KC507 reduce the voltage on it.

A feedback system switches the voltage polarity across the transformer windings by enabling quick MOSFET closing.

Through the use of an electrolytic filter capacitor the energy stored in the transformer core is transferred efficiently to the output.

Stable output voltage is achieved by the teamwork of a Zener diode and an optocoupler.

When the output voltage reaches its low value the Zener diode switches ON.

The optocoupler transistor is triggered by current flowing through the 4N35 optocoupler LED.

By increasing the voltage at the KC507s base the transistor allows it to activate at a lower level on 0R22.

The current sensor 0R22 with KC507 limits the MOSFET the maximum current to 2.27A providing basic short circuit safety.

A ferrite core transformer with four 0.6mm wires coiled around the secondary winding and additional 0.4mm wire windings.

The optocoupler and Zener diode combination gives an output voltage fluctuation upto 4%.

It is simple to adjust the Zener diode voltage and the number of secondary turns at the same ratio for different voltages.

Formulas and Calculations:

Below are the formulas with calculations for Simple 12V 5 Amp SMPS circuit:

This circuit diagram is probably used to specify the voltage deviation (Vdeviation) and maximum current allowed (Imax) for a circuit:

Maximum Current or Imax: = 2.27 A

In this case 2.27 A is the highest current that can safely flow through a component or circuit.

If this current is drawn too much it might malfunction, break or overheat.

It is commonly used in circuit design to ensure that components are not stressed over their current ratings.

Imax can be included in datasheets for electronic components along with other details like operating temperature and minimum voltage.

Vdeviation (Voltage Deviation)= 4%

This figure which in the example is 4% represents the permitted voltage fluctuation from a target level.

A percentage is frequently used to express it.

For example the following voltage range is acceptable if the circuit has a low output voltage of 12V and a Vdeviation of 4%:

Minimum voltage: 12V – (4% of 12V) = 11.52V

Maximum voltage: 12V + (4% of 12V) = 12.48V

When constructing a power supply to produce proper voltage variations around a regulated output voltage Vdeviation is necessary.

Note:

These formulas are used to define a circuits operating limits for voltage and current and assuring stable and safe operation.

Safety Note:

• Beginners are not advised to use this circuit for a 12V 5 Amp switch mode power supply since it is connected to a very dangerous mains voltage.
• Poor circuit design might cause the output to receive mains voltage.
• Even after being disconnected from the mains capacitors may continue to hold harmful voltage.
• Proceed at ones own risk no responsibility is accepted for any property or health damage.

Conclusion:

A Simple 12V 5A SMPS Circuit (Switched Mode Power Supply) offers a reliable, handy and efficient way to power the devices that need a steady 12V DC output at up to 5A current.

Similar to a standard uniform power supply it uses high frequency switching to achieve greater energy efficiency and less heat generation.

Its design makes it suitable for various uses such as embedded systems, tiny motor drives and LED lights.

References:

60 W 12 V 5 V SMPS