If a need arises where you have to use CD4011, you might start to think about how to go further. You already about the use of a CMOS Digital IC. In this situation, you might decide to use IC without understanding how it really works. But do you think that’s the way to go? If you knew it works you will be able to achieve maximum efficiency which will reduce many problems that might arise. Let’s proceed with the characteristics of CMOS and ways of using it.
What is a CMOS integrated circuit?
CMOS integrated circuit is a digital IC that has an important element in the MOSFET. It’s not very important to know its structure thoroughly. Of course, you probably don’t intend to build it on your own, right?
Currently, the internal structure of both P-MOS and N-MOS is on the same chip for lower power consumption. This type of structure is called CMOS (complementary MOS).
This type of digital IC is as widespread as TTL (older). A CMOS belongs to the same family and has the same number as the TTL.
I personally really like to use them. What about you?
Why do you also prefer using them?
Characteristics of CMOS IC:
Let’s take a look at the important features of CMOS. These features clearly show why I love to use them:
- Requires a wide voltage power supply of 3V to 16V;
Imagine you have to use 2×1.5V AA batteries (3 volts) but their efficiency is lower than the voltage level 5V, 9V, or 12V.
See the power supply for CMOS below.
Note: If you are a beginner you must go through this before you move on. For beginners, this way of learning electronics is super easy.
- Avoid entering the input signal that increases or decreases slowly. The reason is that it will cause the IC to use too much power.
- The unused input pin.
We should always connect the unused pins to VDD (V +) or VSS (GND).
Look at the diagram towards the right. It shows a 1kHz clock oscillator using CD4069.
In the diagram shown, we will not use I3 to I6. So we connect it to VDD and VSS.
If we connect it to something else, it will cause the IC malfunction. This causes it to consume more power than usual.
The CMOS input has a very high resistance; hence it is sensitive to various interference signals.
Now let’s take a look at the inside of a CMOS IC. Its producer inserts the proper circuit to solve this problem b there is no harm at being extra careful.
- The input voltage should not exceed VDD (Power Supply voltage). It can only exceed for IC numbers CD4049 and CD4050.
- The signal must never be connected to the CMOS IC once the power supply has been stopped.
- Every type of IC is sensitive to heat. You must not solder the IC pin directly for more than 10 seconds especially if you are a beginner at using an IC socket.
- Make sure that you don’t connect the wrong circuit for example the output of the IC directly connected to the power source is a wrong connection. It may damage the IC. Even if the CMOS has a built-in protection circuit you still must be careful while turning on the power switch or while attaching the power supply.
The proper connection of the circuit is really important as it affects the output of the circuit.
- Be careful while handling the IC.
- You should not bend the legs of the IC as it may cause cracks in its internal structure which in turn affects its lifespan.
Another thing that affects the CMOS is the electrostatic charge. This type of charge is observed regularly around us.
The most dangerous leg of a CMOS is the input pin. The reason is that the resistance of the input pin of this type of IC is usually very high. It will act as the same as insulation to a circuit.
The input pins store the static electricity and pass them anywhere later on.
When it gets accumulated too much there is really no way to discharge it which can damage the circuit from the input area.
IC production technology has developed a lot in recent years. Hence an advancement has been that the input side of the IC has a protection circuit inside and can therefore be not so easily damaged anymore.
But there is still no harm in always being careful. Caution prevents accidents.
I always keep my IC wrapped in a metal sheet or foil, a conductive foil, or an aluminum paper. Then I transfer it to a plastic bag again gradually.
Digital status of CMOS
We are aware that usually, the digital circuits have status “1” and “0”. But how much is the 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 has “0” status.
For example, we are using a 9V battery.
If the voltage level is less than 3V, the status will “0”. On the other hand, if the high voltage level is 6V, the status is “1”.
Here you must be careful because the voltage between 3V to 6V may cause the IC malfunction.
CMOS Power supply
While handling the CMOS its easy to handle power supply. The reason is that it uses a lower current and wide voltage range. Look at the diagram below.
For basic circuits, you can use the 9-volt battery as its power supply.
The important point is that we need to filter both capacitors (C1, C2). They act as transient killers to reduce any noise.
You can also use the 78xx DC regulator series. For example IC-7812, 7815, or others.
Family of CMOS IC
In the assembly of electronic circuits, many different ICs are used. Each of the IC used must have the same features. For example, you should use the same power supply; the signal voltage must be equal, etc. When you connect an IC like this, you will not encounter any problems.
Therefore the manufacturer produces ICs in groups with the same electrical properties. This type of production is named as 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 a project and sell the copyrights to other companies that are made out to use them together for us at a decreased price.
For your understanding, see more pictures and let me give you an example. If you want to use the 4011 NAND GATE, you have many options or numbers to make a choice from. They will have the same leg position and features.
Look at the right: CD4011, MC14011, HD14011, TC14011
Make great circuits using CMOS and enjoy!!
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