CD4066 / 74HC4066 Quad Analog Switch CMOS circuits

What switches is in In digital? 74HC4066/CD4066 is a good answer. Most people use them. Why?

The 4066 is a high-speed CMOS Quad Logic Chip. Which containing with silicon gate Cmos technology. To use as analog switches.

They can turn ON or OFF with external logic signals.

See inside 74HC4066 or 4066. It consists of 4 independent high-speed switches, ABCD block. And, can control either digital or analog signals. While still low power dissipation.

CD4066 / 74HC4066 Pinouts

If I explain not good enough. Let me tell addition.

Imagine the block switch A. We enter logic “high” to a control leg A. Or connect it to Vcc. Then, the switch turns ON or closed circuit. The electrical current can flow both ways. O/I or I/O.

Next, we enter the logic “low” to the control leg A instead. Or connect it to GND. Then, It gets the opened circuit. The current cannot flow like the normal switches

The general features

We can use 4066 easily. It looks like 4011 Nand gate CMOS. They are the same shape, DIP-14. But pinouts are different.

I like it because…

• Wide voltage supply—The maximum supply (Vcc) at pin 14 must not exceed 18V.
• Low resistance—when switched ON has 50 ohms only.
• High resistance—when switched OFF is about 10M
• Very fast switch—can use with TTL or any circuits.

And you can read more detail below.

Features:

• Wide supply voltage: 3V to 15V
• Use low supply current in CMOS technology
• Wide analog input voltage range: 0 to 12V
• High Speed: 7nS at Vcc = 5V
• Low Power Dissipation: 1uA(max) at Ta = 25°C
• High Noise Immunity: Vnih = Vnil = 28% Vcc(Min)
• Low ON Resistance: Ron = 50Ω at Vcc = 9V
• High Degree of Linearity THD = 0.05%(typ) at Vcc = 5V.
• Pin and Function Compatible with 4066B.

Example CD4066 Circuits

Let’s see the example circuits. They may be good ideas for you.

Signal bus controller circuit using CD4066

This is a data bus controller circuit. We connect all the control pins together. To control all ports data. The signal can come in or out. When we enter logic “high”.

In another hand, the signal cannot flow when control pins are low status.

Data selector circuit

We can easily select an input data by simply entering a “high” stage to the DATA select pin. All three other DATA select pins are “Low” stage.

Adding digital voltage control

From the 3A adjustable power supply using LM317 and 2N3055.

Suppose that we want to change the adjusting voltage. To be digital control with any logic signal. For example the Arduino or others.

Digital logic controls voltage 3V, 6V, 9V, and 12V. It is like the above circuit.

Also, It is easy with helping of 74HC4066 analog switches.

If you are interested in this idea. You may use external power supply 5V for this IC. I believe in you can do it.

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