5V High Current Buck Converter Circuit using IC MC34063

Today, many electronic circuits need stable 5V supply.

However, input voltage is not always fixed, sometimes it is 12V and sometimes it can go up to 30V.

Therefore, a buck converter is needed.

This 5V High Current Buck Converter Circuit using IC MC34063 reduces voltage efficiently and it also saves power.

Here, we used the KA34063 IC which is is cheap and popular and alone it gives low current.

So to increase current we used TIP42 transistor, because of this the output current reaches 2A and also the efficiency is much better.

Circuit Working:

Parts List:

First, input voltage is given to circuit as the input voltage can be between 12V to 30V.

Then MC34063 IC starts working as it starts oscillating and it makes switching pulses.

After this the pulses go to TIP42 transistor and this transistor works like current booster.

Because of this, high current flows in inductor L1.

Meanwhile, inductor stores energy and after that it releases energy to output side.

At same time the diode D1 gives current path and this happens when transistor is OFF.

Next, capacitor C3 smooth the voltage, because of this output becomes stable DC.

Then feedback resistors check output voltage as IC reads this voltage and it changes duty cycle.

As a result the output voltage stays constant.

Also, when VR1 is turned the feedback voltage changes and so output voltage also changes.

Formula with Calculations:

Output Voltage Formula:

Vout = 1.25 x (1 + R9 / R10 + VR1)

Values as per circuit:

• R9 is 10k
• R10 is 2.2k
• VR1 is 0 to 10k

Minimum Vout:

Vout = 1.25 x (1 + 10k / 2.2k)

Vout = 2.1V

Maximum Vout:

Vout = 1.25 x (1 + (10k + 10k) / 2.2k)

Vout = 6.9V

How to Build:

To build a 5V High Current Buck Converter Circuit using IC MC34063 follow the below connections steps:

• First, gather all the circuit parts as shown in diagram above.
• Then start with pin 1 of IC is connected to base network of TIP42 through R2.
• Pin 2 of IC is connected to ground.
• Pin 3 of IC is connected to C2 470pF to ground.
• Pin 4 of IC is directly connected to system ground.
• Pin 5 of IC is connected to feedback resistors R9, R10 and VR1.
• Pin 6 of IC is connected to input voltage line of +12V to 30V.
• Pin 7 of IC is connected to R1 to R8 resistor network one end and other end are connected to +12V to 30V Vin supply.
• Pin 8 of IC is connected to pin 1 of IC.
• Q1 TIP42 transistors emitter pin is connected to resistors network from R1 to R8.
• Collector pin is connected to inductor L1 and cathode of D1.
• Base pin is connected to pin 1 and pin 8 of IC through resistor R2.
• Inductor L1 one end is connected to to TIP42 collector and other end to output voltage.
• Capacitor C1 positive end is connected from Vin and negative to GND.
• Capacitor C3 positive end is connected between L1 inductor and resistor R9 and negative to GND.
• At last, resistor R11 and LED are connected in series at Vout supply.

Conclusion:

This 5V High Current Buck Converter Circuit using IC MC34063 is very useful project for beginners.

It is simple and is with low cost and also, it delivers high current.

Because of TIP42 transistor its power handling increases and because of MC34063 the control is easy.

So this circuit is ideal for beginners and it is also good for hobby and repair work.

Finally, with proper assembly it works reliably.

References:

Application of the MC34063 Switching Regulator