This Simple 5V Switch Mode Power Supply Circuit using IC LM2674 work like charger for electronics but better; as it take strong electricity which is more than 5 volt and make it just 5 volt.
A 5V supply provides perfect power for small electronic devices and project boards, also this circuit uses a special chip called the LM2674, which is easy to use and keeps the 5V output stable and steady.
So we can use this circuit and there is no need to worry about our electronics safety as they wont damage from too much power.
Circuit Working:
Parts List:
| Components | Values | Quantity |
|---|---|---|
| Capacitors | Ceramic 10nF | 1 |
| Electrolytic 100µF 50V | 1 | |
| Electrolytic 100µF 10V | 1 | |
| Semiconductors | IC LM2674 | 1 |
| Coil inductor 150µH | 1 | |
| D1 Schottky diode | 1 |
This circuit use 5V power supply called Switch Mode Power Supply which uses one chip IC from National Semiconductor, as this company is good at making these kind of power chips.
Also, these chips are easy to use because they have good guide paper and many people use LM2671 or LM2674 for this.
We can get parts for 3.3V, 5V or 12V output and also some can change voltage if needed; as this power supply can give up to 500mA current and it works fast to 260 kHz switch speed.
Good thing is it does not need big coil or big capacitor so it is small and save power, most time it work with 90% efficiency and sometimes even 96% which is very good!
Furthermore, these ICs also protect from too much heat or too much current with no damage and LM2671 IC has more options it can start slowly with soft start and can match timing with other power supplies.
Hence, this help reduce signal noise like EMC problem and also this circuit makes 5V output and can give up to 500mA current.
Finally, the circuit uses diode D1, a special Schottky diode rated for at least 45V and 3A rated.
Formulas:
This 5V switch-mode power circuit uses the LM2674 IC to step down the voltage efficiently.
Even this chip does many things by itself it is still good to know some basic formula to help with checking how it works and choosing parts.
Inductor Value (L):
L = (Vout * (Vin – Vout)) / (ΔI * fsw)
where,
- L is coil value in henrys.
- Vout is 5V for output voltage.
- Vin input voltage which is between 8V to 40V.
- ΔI is ripple current which is usually 20–40% of output current.
- fsw is switch speed for 260 kHz for IC LM2674.
Be sure coil can take more than 500mA current.
Choosing Output Capacitor (C3):
C3 = Iout / (ΔVout * fsw)
where,
- C3 is capacitor value in farads
- Iout is output current which is 500mA.
- ΔVout is small change for ripple in output voltage.
- fsw is switch frequency at 260 kHz.
Bigger capacitor means less ripple.
Efficiency Formula:
η = (Pout / Pin) * 100%
where:
- η is efficiency in percent.
- Pout is the Vout × Iout
- Pin is the Vin × Iin
Note:
This is short and basic information for exact numbers and better design we need to check the LM2674 datasheet, also, try using simulation tools to help test the design.
How to Build:
To build a Simple 5V Switch Mode Power Supply Circuit using IC LM2674 follow the below mentioned connections steps:
Choose Parts:
- First, pick inductor, capacitor and resistor values by checking LM2674 datasheet and choice should be based on what we need like output voltage, current etc.
Make Circuit Layout:
- Next, build the circuit on breadboard or PCB and follow layout advice from LM2674 datasheet for best working.
Connect Parts:
- Then put all parts together same as circuit diagram in datasheet or application notes.
Power In and Out:
- Now give power to pin 7 of LM2674 DC input and connect the load output to pin 8.
Test the Circuit:
- After that, turn the power ON and check output voltage and current and be sure they match what we need and also check if LM2674 get too hot it should stay cool or warm but not too hot.
Finish Up:
- If everything works good then fix layout and wires properly and if LM2674 gets hot if possible maybe add heat sink to keep it cool.
Note:
- Always check the LM2674 datasheet for correct information and follow all tips for best results.
Conclusion:
To conclude, the Simple 5V Switch Mode Power Supply Circuit using the IC LM2674 provides an easy and effective way to create a 5V switch-mode power supply.
Also, it gives a steady output, so many people use it in different projects that require 5V power.
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