MC34063 Switching Regulator with Buck-Boost Converter Circuits

We often use MC34063 or KA34063 as the main component in the DC-to-DC converter circuit. It is not the best SMPS (Switching Mode Power Supply) IC. But it is widely used enough to be found easily on the market.

They are now very cheap and are starting to make their way into the hobby world. We often see them in many devices, such as car chargers, for instance, to regulate voltage from 12V to 5V converter circuits.

At a current below 1A, no external drivers are required, and the circuit is very simple to build.

The chip can be used in a buck or boost converters, inverting circuits, etc. It is therefore a good IC to replace LM317.

You should have it stocked up for when creating various switching-mode power supplies; it will become useful.

It is both shaped and easy to use, like a 555 timer chip. It is an 8-pin chip. Thus, it is small in size same as IC-555 but features similar to LM317.

What is the function of the MC34063

The MC34063 is a very useful chip. It is a DC-DC converter chip. We can use it as a buck converter, a boost converter, or an invertering switching regulator.

Thus it can function as a step-up converter, a step-down converter. And the inverter with a combination of step-up or step-down functions.

Often we found it on many devices such as car chargers for instance to regulated voltage levels.

The Datasheet for the MC34063.

Its Feature

• Its output current capability is up to 1.5A
• Operation input voltage from 3.0V to 40V
• Current Limiting
• Adjustable Output Voltage (1.2V to 40V) with external resistors
• It can switch power at frequencies up to 100KHz.
• Low Standby Current
• Precision 2% Reference
• Pb−Free Packages are Available

What is the equivalent of MC34063A?

Equivalent MC34063A DC to DC converters are MC34063A, MC33063A, SC34063A, SC33063A, KA34063,NCV33063A, CS51411, ACT4514, and TS2580.

The MC34063 Pinout

We can see the leg position of this IC below. It’s quite simple.

Nowadays, we prefer to use SMD devices because they are small and economical. This IC has a SOIC-8 shape, while the position of the pins remains the same as shown in the figure below.

The basic internal circuit structure

Then, see the Basic internal circuit structure below.

Cr:https://www.onsemi.com/

Some of the components in the diagram above are inside the chip. Including complex details such as switching system, transistor, comparator, and more. It makes our work easier and more convenient.

In addition, the MC34063 has 8 usable pins, which are detailed as follows:

Pins list

1. Pin 6: VCC is a positive leg that must always connect the positive terminal of the source.
2. Pin 4: Ground (GND) is a negative leg that must always connect the negative terminal of the source. 
3. Pin 3: The Timing Capacitor, it is connected to the Oscillator, to control switch power at frequencies up to 100KHz.
4. Pin 7:  Ipk Sense
5. Pin 1: Switch Collector
6. Pin 2: Switch Emitter
7. Pin 8: Driver Collector
8. Pin 5: Comparator Inverting Input to control the output voltage. Do you notice a 1.25V reference regulator block? Yes! It looks like the LM317. We can connect to the output to monitor the voltage and maintain stability.

Well, it may be enough. You might start to get bored.

MC34063 circuits

Next, let’s look at some examples of using the MC34063 in various circuits, as follows:

3-4V to 12V DC Boost Converter

This circuit can convert an input voltage (3.3V-5V) to higher output voltage(12V to 13.8V) at 500mA of current

Read more: 3-4V to 12V DC Boost Converter circuit

12V voltage regulator circuit

This is a 12V stable battery voltage regulator circuit using MC34063. We use it to a 12V battery. Its output voltage is steady at 12V. Although the input voltage change between 5V and 13V.

It is a switch mode power supply. Thus, it has high efficiencies of over 90%. In the circuit below, it uses the MC34063 and a few components. So we can build easily with cheap.

Use IC- MC34063 so easy circuit, Adjustable VR1 for Control Efficiency at 12V 600mA

In the circuit above. This circuit uses a few components. We come to see it.

First of all, to power this chip with connecting +V to VCC pin 6, and the pin 4 to ground.

Next, this sets power for the chip. After that, the input voltage, to VCC and ground. At the same time, we connect a 100uF capacitor. It will filter an excess noise from the power supply out.

Then, Pin 2 connected to the base of internal transistors-Q1-TIP31 to ground.

Pin 3 is the timing capacitor-C2. It determines the switching speed of the circuit.

Pin 5 is inverting terminal of the comparator.

The voltage of the non-inverting terminal is 1.25V from the internal voltage regulator.

To the inverting terminal, we place a resistor network composed of 2 resistors. These decide the gain of the op-amp comparator by the formula, VOUT= 1.25V (1 + R4/R3).

Since we want an output voltage of 12V, R3= 1.5K and R4= 12K.

We use the potentiometer-VR1 to adjust the Efficiency at 12V 600mA

This is how the circuit has its boost functionality.

And this is a classic switch mode power supply using the MC34063 chip to act as a step-up or boost converter.

We can use MC34063 to make many circuits. See the circuits below, you will see other ideas.

12V to 28V Boost DC converter circuit

This boost switching regulator circuit can boost a 12V battery to 28V output at 170mA current.

3.7V to 5V Boost/Step-up DC converter circuit

Here is a 3.7V to 5V boost converter or step-up switching circuit using MC34063 and a few parts,1N5819,100uH. For 200mA-300mA of load current.

Also 12V switch mode power supply

• LM2577 5V to 12V DC Converter step up Voltage Regulator
• LM2575 Switching Regulator 1.2-12V for Solar
• 12V to 16V DC/DC Converter with LM2577

What’s more? You can look other power supply circuits: Click Here

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Apichet Garaipoom

I love electronics. I have been learning about them through creating simple electronic circuits or small projects. And now I am also having my children do the same. Nevertheless, I hope you found the experiences we shared on this site useful and fulfilling.