Know the characteristics of CMOS IC and how to use

Imagine you are using CD4011. You know that it is a CMOS Digital IC. Of course, you may use this IC without understanding enough. But, Is it better? If you know it works. For maximum efficiency, reducing various problems well. Let’s know the characteristics of CMOS and how to use it.

Know the characteristics of CMOS IC and how to use

What is CMOS integrated circuit?

It’s a digital IC with an important element in the MOSFET. We don’t need to know its structure thoroughly. Because you probably don’t think of building it, right?

Currently, the internal structure of both P-MOS and N-MOS is on the same chip for lower power consumption. We call it CMOS (complementary MOS).

This type of digital IC As widespread as TTL (older). Some family the same number as the TTL.

I like to use them, and you?


Characteristics of CMOS

Then, we will look at the important features of CMOS. This is the reason that I love them:

  • Requires a wide voltage power supply of 3V to 16V.

Imagine you can use 2×1.5V AA batteries (3 volts). But the efficiency is lower than the voltage level 5V, 9V, or 12V.
See the power supply for CMOS below.

power supply voltage of CMOS
  • Uses less current than other digital IC.
    For example, the basic Gate chip uses the current of 0.1mA only (in standby mode).

    Even the wristwatch chip uses a CMOS type IC. We only use a small battery. But can be used for up to 1 year. It consumes electricity almost zero.
  • Use 74Cxx series it looks like TTL.
    For example 74C04, a CMOS that is equivalent to the TTL, 7404. This modern CMOS has a high speed. It has a capability equal to TTL.

Note: If you are a beginner should read this before.
Learning electronics for beginners with easy ways


Operating Requirements

  • Must Never enter the power supply to the wrong polarity. Because the IC was broken instantly.
Do not the wrong polarity of power supply
  • Avoid entering the input signal that is rising slowly and decreasing slowly. Because it will cause the IC to use too much power.
  • The unused input pin.

    We should always connect them to VDD (V +) or VSS (GND).

    Look at the right. It is a 1kHz clock oscillator using CD4069.

    We do not use the I3 to I6. So, we connect to VDD and VSS.
Unused input pin on CMOS to ground

Otherwise, it will cause the IC to malfunction. And consume more power than usual.

Because the CMOS input has a very high resistance, Therefore is sensitive to various interference signals.

Now, inside of CMOS IC, even the producer inserts the circuit to solve this problem. But we should always be careful about this.

  • The input voltage should not exceed VDD(Power Supply voltage). Except for IC numbers CD4049 and CD4050.
input voltage should not exceed VDD
  • Do not connect the signal to the CMOS IC. Once the power supply has been stopped.
  • Every type of IC is afraid of the heat. Do not solder the IC pin directly for more than 10 seconds. If a beginner should use an IC socket better.
  • Do not connect the wrong circuit. Such as the output of the IC directly to the power source. It may damage the IC.

    Even if the CMOS has a built-in protection circuit. So be careful.

    When turning on the power switch or enter the power supply.

    We should always check the correct connecting of the circuit, especially the output of the circuit.
not connect output directly source
  • Be careful when handling the IC.
  • Should not bend the legs of the IC. It may cause cracks in the internal structure. Then, Make shorten its lifespan.

Anti Static discharge

Another very scary thing for CMOS is electrostatic. It happens easily around us.

The most dangerous leg is the input pin. The resistance of The input pin of this type of IC is usually very high. It has the same properties as insulation.

This input pins may take static electricity from anywhere to store it.

Static electricity

When it accumulated a lot. There is no way to drain it which can damage the circuit at the input area.

Currently, IC production technology has developed a lot. The input side of the IC has a protection circuit inside. It is therefore not easily damaged anymore.

But for not being careless. Prevent unexpected events.

I keep the IC in a metal sheet or foil, conductive foil, or aluminum paper. Then gradually in a plastic bag again

Keep CMOS on the conductive foil

Digital status of CMOS

We know that digital circuits have the status “1” and “0”.
How much voltage level in the CMOS IC?

We usually specify that 2/3 of the power supply voltage level is “1” and 1/3 of the power supply voltage level is “0” status.

See for example We use a 9V battery.

If the voltage level is less than 3V, the status is “0”. On the other hand, the high voltage level is 6V, the status is “1”.

But be careful, the voltage between 3V to 6V may cause IC to malfunction.

Logic voltage level of CMOS

Read other: CMOS Technical details

CMOS Power supply

Above the CMOS using an easy power supply. Because it uses lower current and wide voltage range. Look at below

For basic circuits, you can use the 9-volt battery as its power supply.

Important, we need filter both capacitors (C1, C2). They are a transient killer to reduce any noise.

9V power supply of CMOS using battery

Also, you can use the 78xx DC regulator series. For example IC-7812, 7815, or others.
Read next: 78xx DC regulator circuit

Family of CMOS IC

In the assembly of electronic circuits. We often use many ICs. Each of them should have the same features. For example, use the same power supply, the signal voltage is equal, etc. When those ICs are connected, Therefore not a problem.

Therefore, the manufacturer so produces ICs in groups with the same electrical properties. We call it the CMOS family.

Examples of different families include:

  • CD40xx is a CMOS IC with RCA being the first manufacturer.
  • The MC140xx family is an IC company from Motorola.
  • The HD140xx family is an IC company from Hitachi.
  • The TC40Hxx family is a high-speed CMOS IC manufactured by Toshiba.
  • etc,

These companies develop and selling copyrights to other companies made out for us to use together. At a decreasing price.

For you to see more pictures Let me give you an example. If you want to use the 4011 NAND GATE. You have many options or numbers. To choose from, with the same leg position and features.

Look at the right: CD4011, MC14011, HD14011, TC14011

Many family CMOS of 4011 NAND Gate IC

Great circuits using CMOS

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I always try to make Electronics Learning Easy.


  1. Adeyemi

    What can be done to avoid between 1/3 and 2/3 Vdd when using analog signal as input? Thank you

    • Hello Adeyemi,

      Thanks for your question. I am happy that you are interested in CMOS Digital ICs.
      Even, it is so easy but so useful, too.

      This problem can be avoided by using digital ICs with Schmitt Trigger features such as CD4093 Nand gate, CD40106 Inverter/Not gate. The output of these ICs has only 2 levels, “1” and “0”. Only. Even if the analog signal on the input is changed in any way.

      If I have free time, will write more articles about them. Please wait for me.

  2. Adeyemi

    Thank you, What can be done to avoid between 1/3 and 2/3 Vdd input voltage so that the ic will not malfunction when using it in circuit with variable input voltage?
    Kindly post a CD4069 ic voltage stabilizer 5 relay circuit

    • “Kindly post a CD4069 ic voltage stabilizer 5 relay circuit”

      Do you want The 5 relay control using CD4069?

      Currently, I don’t have such a circuit. But it’s an interesting concept. I like simple experiments. to use and have knowledge At least teach the children. I will try your circuits. (when I get free)

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